Landslides

A landslide is a form of mass extinction involving a variety of earth movements such as rockfalls, deep slope failure, and shallow debris. Landslides can occur underwater called underwater landscape, coastal and onshore environment. Although it is the primary driving force for gravitational drift, there are other factors that affect the original slope stability. The actual slip usually requires a trigger before it is published, whereas typically, the pre-conditional factors are to create specific subsurface conditions prone to slope failure. The landslides should not be mixed with the mud which is a mass depletion form associated with a very rapid rash flow partially or totally liquefied by adding significant quantities of water to the starting material.

Contents

Causes of Landslides
Types of Landslides
Rockfalls
Debris flow
Creep
Slumps
Overpressured zones (including gas and shallow water flows)
Recent “Gushers”
Mudflows:
Diapirism:
Volcanism/Volcanoes:

Causes of Landslides

There are several natural and human-related factors that can contribute to the occurrence of landslides. Here are some of the main causes of landslides:

Geological Factors: Landslides can be triggered by the geological composition and structure of the ground. This can include the type of soil or rock, the slope of the land, and the presence of water or other fluids.
Meteorological Factors: Extreme weather events, such as heavy rainfall, snowmelt, or rapid temperature changes, can increase the likelihood of landslides. This is because these weather conditions can saturate the ground and weaken the stability of the soil or rock.
Human Factors: Human activities, such as deforestation, mining, construction, and irrigation, can also contribute to landslides. These activities can alter the natural landscape and destabilize the ground, making it more susceptible to landslides.
Earthquakes: Earthquakes can also trigger landslides by shaking the ground and causing rocks and soil to slide down slopes.
Volcanic Activity: Volcanic eruptions can trigger landslides by causing the ground to become unstable and by generating large volumes of loose material that can slide down slopes.

Understanding the causes of landslides is important for developing effective mitigation strategies to reduce the impacts of these natural hazards on human communities and infrastructure.

Types of Landslides

There are several different types of landslides that can occur, each with its own characteristics and causes. Here are some of the main types of landslides:

Rockfalls: Rockfalls occur when rocks or boulders become detached from a steep slope and fall or roll down the slope. These types of landslides are often triggered by weathering and erosion of the rock face, as well as by seismic activity.
Debris Flows: Debris flows, also known as mudflows, occur when a mixture of soil, rock, and water flows rapidly down a slope. These types of landslides are often triggered by heavy rainfall or rapid snowmelt, which can saturate the ground and destabilize the slope.
Landslides: Landslides occur when a mass of soil or rock slides down a slope. These types of landslides can be triggered by a variety of factors, including heavy rainfall, seismic activity, and human activities such as construction or mining.
Creep: Creep is a slow, continuous movement of soil or rock down a slope. This type of landslide is often caused by long-term weathering and erosion of the slope, as well as by changes in soil moisture and temperature.
Slumps: Slumps occur when a block of soil or rock rotates and slides down a curved slope. These types of landslides are often triggered by a combination of geological factors, such as the type of soil or rock and the slope angle.

Understanding the different types of landslides is important for predicting and mitigating their impacts on human communities and infrastructure. Each type of landslide requires different mitigation strategies, depending on its characteristics and causes.

Rockfalls

Rockfalls are a type of landslide in which rocks or boulders become detached from a steep slope and fall or roll down the slope. They can occur in a variety of environments, including mountainous regions, cliffs, and road cuts. Rockfalls can be triggered by a variety of factors, including weathering and erosion of the rock face, seismic activity, and human activities such as construction or mining.

Rockfalls can have significant impacts on human communities and infrastructure. They can cause damage to buildings, roads, and other infrastructure, as well as pose a risk to human life. In areas with high levels of tourism, rockfalls can also impact recreation and the local economy.

There are several strategies for mitigating the impacts of rockfalls. One approach is to identify areas with a high risk of rockfalls and implement protective measures such as rockfall barriers, catchment ditches, and wire mesh netting to stabilize the slope and prevent rocks from falling onto roads and other infrastructure. Another approach is to monitor high-risk areas using remote sensing techniques such as LiDAR and satellite imagery to detect changes in slope stability and potential rockfall hazards. Additionally, public education and awareness campaigns can help to reduce the risk of injury and damage by encouraging people to stay away from high-risk areas and to report any potential hazards to local authorities.

Debris flow

A Debris Flow is basically a fast-moving landslide made up of liquefied, unconsolidated, and saturated mass that resembles flowing concrete. In this respect, they are not dissimilar from avalanches, where unconsolidated ice and snow cascades down the surface of a mountain, carrying trees and rocks with it.

A common misconception is to confuse debris flows with landslides or mudflows. In truth, they differ in that landslides are made up of a coherent block of material that slides over surfaces. Debris flows, by contrast, are made up of “loose” particles that move independently within the flow.

Similarly, mud flows are composed of mud and water, whereas debris flows are made up larger particles. All told, it has been estimated that at least 50% of the particles contained within a debris flow are made-up of sand-sized or larger particles (i.e. rocks, trees, etc).

Creep

Creep is a type of landslide that involves slow, continuous movement of soil or rock down a slope. Unlike other types of landslides that occur suddenly, creep can occur over a long period of time, often years or decades. Creep is caused by a combination of factors, including long-term weathering and erosion of the slope, changes in soil moisture and temperature, and the angle of the slope.

The movement in creep is typically gradual and can be difficult to detect. However, over time, the movement can cause damage to buildings, roads, and other infrastructure that is built on or near the slope. In some cases, the movement can also cause trees and other vegetation to tilt or bend, providing a visible indication of the problem.

There are several approaches for mitigating the impacts of creep. One strategy is to monitor high-risk areas using instruments such as tilt meters and GPS to detect changes in slope movement and potential hazards. Another approach is to stabilize the slope using methods such as revegetation, terracing, and the installation of drainage systems to reduce water infiltration and prevent erosion. In some cases, it may be necessary to relocate buildings and other infrastructure away from high-risk areas to avoid the potential for damage and injury.

Overall, understanding the factors that contribute to creep and implementing appropriate mitigation strategies can help to reduce the risk of damage and injury from this type of landslide.

Slumps

Ordu: a major slump type landslide in Turkey

Slumps are a type of landslide that involves the downward movement of soil or rock along a curved surface. They typically occur in areas with steep slopes and can be triggered by a variety of factors, including heavy rainfall, changes in the water table, and human activities such as excavation and construction.

In a slump, the slope of the ground becomes concave, and the soil or rock moves downward and outward along a curved surface. The movement can be relatively slow or fast, depending on the conditions that triggered the slump. Slumps can cause damage to buildings, roads, and other infrastructure that is built on or near the slope, and can also pose a risk to human life.

There are several strategies for mitigating the impacts of slumps. One approach is to identify areas with a high risk of slumping and implement protective measures such as retaining walls, drainage systems, and slope stabilization techniques to reduce the risk of movement. Another approach is to monitor high-risk areas using instruments such as inclinometers and GPS to detect changes in slope movement and potential hazards.

Additionally, public education and awareness campaigns can help to reduce the risk of injury and damage by encouraging people to stay away from high-risk areas and to report any potential hazards to local authorities. Overall, understanding the causes of slumps and implementing appropriate mitigation strategies can help to reduce the risk of damage and injury from this type of landslide.

Overpressured zones (including gas and shallow water flows)

Overpressured zone is oil and gas blast out of underground trap machanism to under high pressure. Usually these zones occur oil and gas drilling process

Recent “Gushers”

During the 1991 Gulf War, the retreating Iraqi soldiers dynamited the wellheads off more than six hundred Kuwati oil wells, creating one of the biggest man-made environmental disasters in history. Since most Kuwati wells flow without pumps under their own great pressure, the oil and gas erupted from the ground with tremendous force. It was first estimated that it would take 2 years to repair all the wells. However, the heroic and extremely dangerous job was actually done in about six months.

Mudflows:

Mudflows, also known as debris flows, are a type of landslide that involve the rapid movement of a mixture of water, rock, soil, and other debris down a slope. They are often triggered by heavy rainfall, snowmelt, or other factors that cause the saturation of soil and the destabilization of slopes. Mudflows can be highly destructive and can cause significant damage to buildings, roads, and other infrastructure in their path. Mitigation strategies for mudflows include the construction of barriers, the installation of drainage systems, and the stabilization of slopes.

Diapirism:

Diapirism is a geological process that involves the upward movement of a dense, viscous material such as magma or salt, through less dense surrounding rock. This process can cause significant changes in the structure of the surrounding rock and can create structures such as salt domes and mud volcanoes. Diapirism can have both positive and negative impacts on human activities, depending on the location and magnitude of the process. For example, salt domes can be a valuable source of oil and gas, while mud volcanoes can pose a hazard to infrastructure and the environment.

Volcanism/Volcanoes:

Volcanism is the process by which magma, ash, and other volcanic materials are expelled from a volcano onto the Earth’s surface or into the atmosphere. Volcanoes are typically found at tectonic plate boundaries, where magma can rise to the surface and erupt. Volcanic eruptions can be highly destructive and can cause significant damage to buildings, infrastructure, and the environment. Mitigation strategies for volcanic hazards include the development of monitoring systems to detect and predict eruptions, the establishment of evacuation plans for at-risk areas, and the construction of barriers to protect infrastructure from volcanic materials such as ash and lava.

Magical Spotted Lake

The lake, which is formed in the shape of a spotted leopard pattern, is located in Canada’s Okanagan Valley. It is one of the remarkable wonders of the world and calls “the most magical place in Canada”. It initially looks like other lakes, but in the summer months when most of the water evaporates, hundreds of abundant salty pools remain. It contains different minerals in yellow and blue colors. Minimal life survives due to the extremely salty condition of the lake.

This lake is not only a remarkable physical feature, but also a very important historical and spiritual site for the local First Nation Peoples.

Contents

Geology of Spotted Lake
Formation of Colors and Spots
History
Scientific Significance

Geology of Spotted Lake

Spotted Lake is a saline endorheic lake, which means that it has no outflow and is fed by underground springs and precipitation. The lake covers an area of approximately 15 hectares and is relatively shallow, with a maximum depth of around 3 meters.

What makes Spotted Lake so unique are the mineral deposits that have formed around its edges. These deposits have been created over centuries of evaporation and precipitation, leaving behind a stunning mosaic of colorful spots.

The spots are actually mineral deposits, created by the high levels of minerals and salts in the lake’s water. The lake’s mineral composition includes calcium, magnesium, sodium, and sulfates, among others. These minerals are concentrated as the lake water evaporates, leaving behind a residue of colorful minerals and salts.

The colors of the mineral spots depend on the specific mineral composition and the amount of sunlight and water present in the area. For example, the blue spots are typically composed of magnesium sulfate, while the green spots are often made up of magnesium sulfate and calcium carbonate.

Spotted Lake’s unique mineral composition and distinctive patterns have made it an important site for scientific study. Scientists are interested in understanding how the mineral deposits form and change over time, and what this can tell us about the geological processes that shape our planet’s surface.

Overall, Spotted Lake is a remarkable geological wonder that provides insight into the complex interactions between water and minerals. Its mineral-rich waters and unique patterns have inspired wonder and awe in visitors and scientists alike.

Formation of Colors and Spots

Groundwater, the crimes of falling snow and rains fill these pools. However, when the weather is hot and dry in the summer months, most of the water evaporates and leaves behind colored pools separated by minerals. Colored pools are different mineral concentrations of compounds such as calcium, sodium sulfate and magnesium sulfate. Its different colors are because it contains a variety of different minerals. It contains 8 different minerals, extremely low amounts of silver and titanium. He estimates that around 400 salty pools rich in sulfate, magnesium, titanium, sodium and other minerals adorn this lake during the summer months. Magnesium sulfate, which crystallizes in summer, makes an important contribution to the spot color. During the summer, the minerals left in the lake harden, forming natural “gates” around and between the spots.

History

The First Nations of the Okanagan Valley originally called it Kliluk. The Kliluk, the spotted lake, has been revered by the people here for centuries as therapeutic. During the First World War, the minerals in this lake were used as ammunition needed. It is said that the old version was more eye-catching than the present.

Scientific Significance

Spotted Lake is an important site for scientific research because of its unique mineral composition and the complex geological processes that have created its distinctive patterns.

One of the main areas of scientific interest is understanding how the mineral deposits in Spotted Lake form and change over time. These deposits are created by the high levels of minerals and salts in the lake’s water, which are concentrated as the water evaporates. By studying the composition and structure of these mineral deposits, scientists can gain insights into the chemical and physical processes that are involved in their formation.

Another area of scientific interest is understanding the role of Spotted Lake in the broader geological context of the region. Spotted Lake is located in an area known as the Okanagan Valley, which is a region of active tectonic activity. By studying the geological features of Spotted Lake and its surroundings, scientists can better understand the complex geological history of the region and the ongoing processes that are shaping the landscape.

Spotted Lake also provides important insights into the interactions between water and minerals, which are important for understanding the global water cycle and the role of minerals in supporting life on Earth. The unique conditions at Spotted Lake have led to the formation of rare minerals that are not commonly found elsewhere, making it an important site for mineralogical research.

Overall, Spotted Lake is an important site for scientific research that offers valuable insights into the geological processes that shape our planet’s surface, as well as the role of minerals and water in supporting life. Its unique mineral composition and patterns have made it a fascinating subject for study and exploration.

Coal

Coal is a non-clastic sedimentary rock. They are the fossilized remains of plants and are in flammable black and brownish-black tones. Its main element is carbon, but it can also contain different elements such as hydrogen, sulfur and oxygen. Unlike coal minerals, it does not have a fixed chemical composition and crystal structure. Depending on the type of plant material, varying degrees of carbonization and the presence of impurities, different types of coal are formed. There are 4 recognized varieties. Lignite is the lowest grade and is the softest and least charred. Sub-bituminous coal is dark brown to black. Bituminous coal is the most abundant and is often burned for heat generation. Anthracite is the highest grade and most metamorphosed form of coal. It contains the highest percentage of low-emission carbon and would be an ideal fuel if it weren’t for comparatively less.

Coal is mainly used as a fuel. Coal has been used for thousands of years, but its real use began with the invention of steam engines after the industrial revolution. Coal provides two-fifths of electricity production worldwide and coal is used as the main fuel in iron and steel production facilities.

Name origin: The word originally took the Old English form col from the Proto-Germanic *kula(n), which is supposed to derive from the Proto-Indo-European root *g(e)u-lo- “live coal”.

Color: Black and Brownish black

Hardness: Changeable

Grain size: Fine grained

Group: Non-Clastic Sedimentary Rock

Contents

Coal Classification
Historical significance
Chemical composition
Physical properties
Mining and processing of coal
Extraction techniques (surface and underground mining)
Processing methods (cleaning, crushing, grading, etc.)
Coal Composition
Coal Formation
Occurrence of Coal
Coal Characteristics and Properties
Intensity
Porosity
Reflectivity
Other features
Economic and social importance of coal
Summary of Key Points
References

Coal Classification

As geological processes put pressure on dead biotic material over time under favorable conditions, the degree or order of metamorphic successively increases as follows:

Lignite, the lowest level of coal, the most harmful to health, is used almost exclusively as a fuel for electric power generation

Jet, a compact form of lignite, sometimes polished; Upper Paleolithic Lower-bituminous coal, whose properties range from those of lignite to bituminous coal, was primarily used as an ornamental stone as it was used as a fuel for steam-electric power generation.

Bituminous coal, a dense sedimentary rock, usually black, but sometimes dark brown, often with well-defined bands of shiny and dull material. It is primarily used as a fuel in the production of steam-electric power and in the production of coke. In the UK it is known as steam coal and has historically been used to raise steam in steam locomotives and ships.

Anthracite, the highest grade of coal, is a harder, glossy black coal used primarily for residential and commercial space heating.

Graphite is difficult to ignite and is not commonly used as a fuel; it is most commonly used in pencils or powdered for lubrication.

Channel coal (sometimes called “candle coal”) is a variety of fine-grained, high-grade coal composed primarily of liptinite with significant hydrogen content.

There are several international standards for coal. The classification of coal is generally based on the content of volatile substances. But the most important distinction is thermal coal (also known as steam coal), which is burned to generate electricity through steam; and metallurgical coal (also known as coking coal), which is burned at high temperature to make steel.

Historical significance

Coal has played an important role in human history and has been used as a source of fuel for thousands of years. In ancient times, coal was used to heat and cook food, and for warmth. During the Industrial Revolution, coal became the primary source of energy for powering steam engines and machinery, leading to significant technological advancements in transportation, manufacturing, and other industries. The use of coal also led to the development of mining as a major industry, and helped to spur economic growth in many parts of the world. However, coal use has also been associated with significant environmental impacts, including air and water pollution, and has been a major contributor to climate change. As a result, efforts are underway to transition to cleaner sources of energy and reduce dependence on coal.

Chemical composition

Coal is primarily composed of carbon, hydrogen, oxygen, nitrogen, and sulfur. The exact composition of coal varies depending on its age and origin, but generally, coal can be classified into four major types based on its carbon content: lignite, sub-bituminous, bituminous, and anthracite. Lignite is the youngest type of coal and contains the least amount of carbon, while anthracite is the oldest and has the highest carbon content. Generally, coal with higher carbon content has a higher energy content and burns more efficiently. Coal also contains varying amounts of minerals such as silica, alumina, iron, calcium, sodium, and potassium, which can affect its combustion properties and environmental impact when burned.

Physical properties

Coal has a variety of physical properties, including:

Color: Coal can range in color from black to brown to grayish.
Hardness: Coal can range in hardness from very soft and crumbly, like graphite, to very hard, like anthracite.
Density: Coal has a lower density than many rocks and minerals, making it relatively lightweight.
Porosity: Coal can be very porous, with small spaces between the coal particles.
Conchoidal fracture: Coal often fractures in a smooth, curved pattern, known as conchoidal fracture.
Luster: Coal has a dull to shiny luster, depending on the type of coal.
Streak: Coal produces a black or dark brown streak when rubbed on a white, unglazed porcelain plate.

The physical properties of coal are important for its mining, processing, and use. For example, the hardness of the coal can affect the type of mining method used, while the porosity and density can affect the processing and transportation of the coal.

Mining and processing of coal

Coal is typically extracted from underground or surface mines. Underground mining methods include room and pillar, longwall, and retreat mining, while surface mining methods include strip mining, mountaintop removal, and open-pit mining.

In the room and pillar mining method, tunnels are dug into a coal seam and pillars of coal are left to support the roof. In longwall mining, a long wall of coal is mined in a single slice, while the roof over the mined-out area collapses behind the mining machine. Retreat mining involves the removal of pillars from a previously mined area.

In surface mining, the overlying rock and soil are removed to access the coal. This process can be done by strip mining, in which the overburden is removed in strips, or by mountaintop removal, in which entire mountaintops are removed to access the coal. Open-pit mining is another surface mining technique, in which a large pit is excavated to extract the coal.

Once the coal has been extracted, it is processed to remove impurities and prepare it for use. The processing may include crushing, screening, and washing to remove rock and other impurities, as well as drying to reduce the moisture content of the coal. Coal may also be treated with chemicals to remove sulfur and other impurities, a process known as coal cleaning.

Extraction techniques (surface and underground mining)

Coal mining can be divided into two broad categories: surface mining and underground mining.

Surface mining involves removing the overlying rock, soil, and vegetation to expose the coal seam. This is usually done with large machines that remove the overburden (the material above the coal seam) in layers. There are different surface mining methods, including strip mining, open-pit mining, mountaintop removal mining, and highwall mining. In strip mining, the overburden is removed in long strips, while in open-pit mining, the overburden is removed in a large pit. Mountaintop removal mining involves removing the entire top of a mountain to access the coal seam, while highwall mining is used to recover coal from an exposed vertical face or cliff.

Underground mining involves digging tunnels or shafts into the earth to reach the coal seam. There are two main types of underground mining: room and pillar mining, and longwall mining. In room and pillar mining, the coal seam is mined in a series of rooms, leaving pillars of coal to support the roof. In longwall mining, a machine called a shearer moves back and forth along the coal seam, cutting the coal and dropping it onto a conveyor belt. The roof is supported by hydraulic supports as the machine advances.

After the coal is extracted, it may be processed to remove impurities and prepared for use. The processing may involve crushing, screening, and washing to remove rocks and other materials that are mixed with the coal. The coal may also be treated with chemicals to remove sulfur and other impurities, or it may be converted to liquid or gaseous fuels.

Processing methods (cleaning, crushing, grading, etc.)

After coal is mined, it often needs to be cleaned and processed to remove impurities and prepare it for use. The exact processing methods used can vary depending on the type of coal and its intended use.

One common method of processing coal is through a process known as “washing,” which involves using water, chemicals, and mechanical equipment to separate the coal from impurities like rock, ash, and sulfur. The coal is crushed and mixed with water and chemicals to create a slurry, which is then passed through a series of screens and cyclones to separate the coal from the other materials. The separated coal is then further processed to remove any remaining impurities and graded based on size.

Other processing methods can include crushing and grinding the coal to make it suitable for burning or other uses, as well as processes to remove sulfur and other pollutants from the coal. Depending on the intended use of the coal, additional processing steps may also be required, such as carbonization to produce coke for use in the steel-making process.

Coal Composition

The composition of coal can be analyzed in two ways. The first is reported as a close analysis (moisture, volatile matter, fixed carbon and ash) or a final analysis (ash, carbon, hydrogen, nitrogen, oxygen and sulfur). A typical bituminous coal may have a final analysis on a dry, ash-free basis of 84.4% carbon, 5.4% hydrogen, 6

ASH COMPOSİTİON, WEİGHT PERCENT
SiO ₂	20-40
Al ₂O ₃	10-35
Fe ₂O ₃	5-35
CaO	1-20
MgO	0.3-4
TiO ₂	0.5-2.5
Na ₂O & K ₂O	1-4
SO ₃	0.1-12

Coal Formation

The process of turning dead vegetation into coal is called coalification. In the geological past there were low wetlands and dense forests in various regions. The dead vegetation in these areas has generally started to biodegrade and transform with mud and acidic water.

This trapped the carbon in huge peat bogs that were eventually buried deep by sediments. Then, over millions of years, the heat and pressure of the deep burial caused a loss of water, methane, and carbon dioxide and increased carbon content.

The grade of coal produced depended on the maximum pressure and temperature reached; Lignite (also called “brown coal”) and sub-bituminous coal, bituminous coal or anthracite (also called “hard coal” or “hard coal”) produced under relatively mild conditions is produced with increasing temperature and pressure.

Of the factors involved in charring, temperature is much more important than pressure or burial time. Sub-bituminous coal can form at temperatures as low as 35 to 80 °C (95 to 176 °F), while anthracite requires a temperature of at least 180 to 245 °C (356 to 473 °F).

Although coal is known from most geological periods, 90% of all coal deposits were deposited during the Carboniferous and Permian periods, which represent only 2% of Earth’s geological history.

Occurrence of Coal

Coal is a common energy and chemical source. Terrestrial plants necessary for the development of coal were not abundant until the Carboniferous period (358.9 million to 298.9 million years ago), large sedimentary basins containing rocks of Carboniferous age and younger are known on almost every continent, including Antarctica. The presence of large coal deposits in regions with currently arctic or subarctic climates (such as Alaska and Siberia) is due to climate changes and tectonic movement of crustal plates that have moved older continental masses over the Earth’s surface, sometimes through the subtropical and even tropics. regions. Some areas (like Greenland and most of northern Canada) lack coal because the rocks found there predate the Carboniferous Period, and these regions, known as continental shields, lack the abundant terrestrial plant life needed for the formation of large coal deposits.

Coal Characteristics and Properties

Many of the properties of coal vary with factors such as its composition and the presence of mineral matter. Different techniques have been developed to examine the properties of coal. These are X-ray diffraction, scanning and transmission electron microscopy, infrared spectrophotometry, mass spectroscopy, gas chromatography, thermal analysis, and electrical, thermal analysis, and electrical, optical and magnetic measurements.

Intensity

Knowing the physical properties of coal is important in the preparation and use of coal. For example, coal density ranges from about 1.1 to about 1.5 megagrams per cubic metre, or grams per cubic centimeter. Coal is slightly denser than water and significantly less dense than most rocks and mineral matter. Density differences make it possible to improve the quality of a coal by removing most of the rock matter and sulfide-rich particles through heavy liquid separation.

Porosity

Coal density is controlled in part by the presence of pores that persist throughout charring. Pore sizes and pore distribution are difficult to measure; however, pores appear to have three size ranges:

(1) macropores (diameter greater than 50 nanometers),

(2) mesopores (2 to 50 nanometers in diameter), and

(3) micropores (diameter less than 2 nanometers).

(One nanometer equals 10−9 metres.) Most of a coal’s effective surface area—about 200 square meters per gram—is found in the pores of the coal, not on the outer surface of a piece of coal. The presence of pore space is important in coke production, gasification, liquefaction and high surface area carbon production to purify water and gases. For safety reasons, coal pores may contain significant amounts of adsorbed methane, which can be released during mining operations and form explosive mixtures with air. The risk of explosion can be reduced by adequate ventilation or prior removal of coalbed methane during mining.

Reflectivity

An important property of coal is its reflectivity (or reflectivity), that is, its ability to reflect light. Reflectivity is measured by shining a monochromatic light beam (with a wavelength of 546 nanometers) onto a polished surface of vitrinite macerals in a charcoal sample and measuring the percentage of reflected light with a photometer. Vitrinite is used as its reflectivity gradually changes with increasing degree. Fusinite reflections are very high due to its coal origin and liptinites tend to disappear with increasing degrees. Although very little of the incident light is reflected (ranging from a few tenths of a percent to 12 percent), the value increases with degrees and can be used to grade most coals without measuring the percentage of volatile matter present.

Other features

Other properties such as hardness, grindability, ash fusion temperature, and free swelling index (a visual measurement of the amount of swelling that occurs when a coal sample is heated in a closed crucible) can affect coal mining and preparation. as well as the way a coal is used. Hardness and grindability determine the types of equipment used for mining, crushing and grinding, in addition to the amount of power consumed in their operations. Ash fusion temperature affects furnace design and operating conditions. The free swelling index provides preliminary information on the suitability of a coal for coke production.

Economic and social importance of coal

Coal is an important natural resource that has played a significant role in the development of the modern world. Its economic and social importance can be seen in several areas:

Energy production: Coal is one of the primary sources of energy used for power generation. It is burned in power plants to produce electricity, which is used to power homes, businesses, and industries.
Steel production: Coal is also a key ingredient in the production of steel. When heated, coal releases carbon, which is used to reduce iron ore to iron. This iron is then used to produce steel, which is an essential material for construction, infrastructure, and many other applications.
Job creation: The mining and processing of coal creates jobs and contributes to local economies in many countries. The industry employs a large number of people, including miners, engineers, geologists, and other professionals.
Transportation: Coal is often transported long distances by rail or ship to reach its destination, which can create jobs and contribute to the economy of the areas through which it passes.
Affordable energy: Coal is often a more affordable source of energy compared to other sources, which can help keep energy costs low for consumers and businesses.
Chemical products: Coal is also used as a raw material in the production of a range of chemical products, including plastics, synthetic fibers, fertilizers, and other chemicals.

However, the use of coal also has significant environmental impacts, including greenhouse gas emissions and other air pollutants, as well as negative effects on water quality and land use. These impacts must be carefully considered in any evaluation of the economic and social importance of coal.

Summary of Key Points

Here are some key points about coal:

Coal is a fossil fuel that is formed from the remains of ancient plants that lived millions of years ago.
There are four main types of coal: lignite, sub-bituminous, bituminous, and anthracite, each with different properties and uses.
Coal is an abundant and relatively cheap source of energy, making it an important fuel for power generation, heating, and industrial processes.
Coal mining can have significant environmental and social impacts, including land disturbance, water pollution, and health risks for workers and nearby communities.
Efforts are underway to develop cleaner coal technologies, such as carbon capture and storage, to reduce the environmental impact of coal use.

References

Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
Kopp, O. C. (2020, November 13). coal. Encyclopedia Britannica. https://www.britannica.com/science/coal-fossil-fuel
Wikipedia contributors. (2021, October 26). Coal. In Wikipedia, The Free Encyclopedia. Retrieved 09:57, November 1, 2021, from https://en.wikipedia.org/w/index.php?title=Coal&oldid=1051971849

Amber

Amber is a fascinating organic gemstone that has captured human fascination for millennia. It’s not a mineral, but rather a fossilized resin from ancient trees. This unique material has played a significant role in various cultures and has been used for both decorative and practical purposes.

Amber is a solidified resin that originated from coniferous trees, primarily in the Pinaceae family, during prehistoric times. Resin is the sticky substance that oozes from trees when they are wounded, serving as a protective mechanism against pests and pathogens. Over time, this resin can become buried and undergo a process of fossilization, transforming into amber.

Amber’s composition is primarily carbon, hydrogen, and oxygen, with traces of sulfur. It’s relatively lightweight and can vary in color from pale yellows and oranges to darker reds and browns. The coloration is influenced by factors such as the type of tree it originated from, the presence of impurities, and the length of time it underwent fossilization.

Formation of Amber:

The journey of amber begins when resin flows from trees as a protective response to injuries. This resin can trap various organic materials, such as insects, plant matter, and even air bubbles. Over time, the resin can fall to the ground, get carried by water, and eventually become buried by sediment. The pressure and heat from geological processes cause the resin to polymerize, gradually solidifying it into amber.

The process of amber formation is a slow one, taking millions of years. During this time, the resin undergoes chemical changes that contribute to its unique properties, including its distinct transparency and ability to hold preserved organisms.

Significance and Historical Uses:

Amber has held cultural and commercial significance for countless societies throughout history. Its captivating appearance, often resembling drops of sunlight trapped within a stone, led many civilizations to attribute it with mystical and protective qualities. Amber was frequently used in jewelry and amulets for adornment and as a symbol of status.

In ancient times, amber was traded along extensive routes, forming part of the fabled Amber Road that connected Northern Europe to the Mediterranean. It was particularly valued by the ancient Greeks and Romans, who associated it with the gods and believed it had healing properties.

Amber’s ability to preserve prehistoric organisms is one of its most remarkable traits. Insects, plants, and even small animals have been found perfectly preserved within amber, providing valuable insights into ancient ecosystems and the evolution of life on Earth.

In more recent times, amber continues to be cherished for its aesthetic and historic value. It’s used in various forms of jewelry, carvings, and decorative art. Additionally, modern science has utilized the fossilized inclusions in amber to study the biology of ancient organisms and gain a better understanding of Earth’s past.

In conclusion, amber is a captivating gemstone that offers a window into the ancient past. Its formation from fossilized tree resin, coupled with its historical significance and uses, makes it a truly unique and cherished material in both cultural and scientific realms.

Contents

Geological Formation
Properties
Types of Amber
Amber as a Gemstone
Occurrence and Locations

Geological Formation

The process through which tree resin transforms into amber is a complex one, involving several stages over millions of years. Here’s a detailed breakdown of the formation process:

Resin Exudation: When certain types of trees, particularly conifers in the Pinaceae family, experience injuries or stress, they release resin as a defense mechanism. This resin is a sticky substance that oozes from the tree’s wounds, sealing them and protecting against pests, pathogens, and environmental stressors.
Transport and Accumulation: The resin can flow down the tree’s bark and collect on the ground or other surfaces. Over time, various materials such as insects, plant debris, and air bubbles might get trapped within the sticky resin.
Burial: If the resin isn’t disturbed or degraded, it can become buried by sediment or transported by water, eventually reaching riverbeds, lakes, or coastal areas. Burial prevents the resin from being exposed to air, which helps in preserving its organic components.
Diagenesis: Under the pressure and heat of geological processes, the resin undergoes diagenesis, a series of chemical changes. Polymerization occurs, where the volatile components of the resin evaporate, and the remaining complex organic compounds bond together, forming a solid substance.
Hardening and Fossilization: Over time, the polymerized resin hardens further, and its structure becomes more crystalline. The process of fossilization involves the infiltration of minerals from surrounding sediments, which can contribute to the final color and appearance of the amber.
Tectonic Movements and Uplift: Geological processes such as tectonic movements, erosion, and uplift bring amber deposits closer to the surface. This can expose them to weathering and erosion, allowing them to be discovered by humans.

Factors Influencing Preservation and Transformation:

Several factors influence the preservation and transformation of resin into amber:

Type of Resin: Different tree species produce resins with varying chemical compositions. Some resins are more conducive to amber formation due to their higher levels of polymerizable compounds.
Environmental Conditions: The conditions of the environment where the resin is deposited play a role. Burial in low-oxygen, anaerobic conditions helps prevent decay and decomposition.
Pressure and Temperature: The pressure and temperature experienced by the buried resin influence the speed and extent of its polymerization and hardening.
Mineral Content: The minerals present in the surrounding sediments can infiltrate the resin during fossilization, affecting its appearance and properties.
Time: Amber formation is a slow process, taking millions of years. The longer the resin is buried, the more extensive the polymerization and fossilization processes become.

Geological Time Periods and Major Amber Deposits:

Amber deposits are associated with specific geological time periods, and they offer insights into the ancient environments and ecosystems of those times. Some major amber deposits include:

Baltic Amber (Eocene): The most famous and commercially valuable amber comes from the Baltic region (Northern Europe). The majority of Baltic amber is dated to the Eocene epoch, which spanned from about 56 to 33.9 million years ago.
Dominican Amber (Miocene to Pleistocene): Found in the Dominican Republic and neighboring areas, this amber ranges in age from the Miocene (about 23 to 5.3 million years ago) to the Pleistocene (about 2.6 million to 11,700 years ago).
Mexican Amber (Miocene): Mexican amber is primarily from the mid-Miocene period, around 15 to 23 million years ago, and is found in regions like Chiapas.

These major amber deposits provide windows into diverse ancient ecosystems, offering scientists valuable insights into the flora, fauna, and climatic conditions of the past.

Properties

Physical Properties:

Hardness: Amber ranks around 2 to 3 on the Mohs scale of hardness, which means it is relatively soft compared to other gemstones and can be scratched easily by harder materials.
Density: Amber is relatively lightweight, with a density ranging from 1 to 1.2 g/cm³.
Transparency: Amber is often transparent to translucent, allowing light to pass through it with varying degrees of clarity.
Luster: Amber has a resinous or vitreous luster when polished, giving it a shiny appearance.
Electrostatic Properties: Amber can develop static electricity when rubbed, a phenomenon known as “electrostatic charging.” This property was famously observed by the ancient Greeks, who named it “elektron,” which eventually led to the term “electricity.”

Chemical Properties:

Composition: Amber is primarily composed of carbon, hydrogen, and oxygen, with minor amounts of sulfur. The complex organic compounds in amber result from the polymerization of the original tree resin.
Volatility: Over time, volatile components in the resin evaporate, leaving behind more stable compounds that contribute to amber’s preservation.
Flammability: Amber is flammable and can burn with a smoky, aromatic flame due to its organic composition.

Types of Amber

Amber can be classified into different types based on its origin, characteristics, and geological age. Some notable types include:

Baltic Amber: Originating primarily from the Baltic Sea region (Northern Europe), Baltic amber is one of the most well-known and sought-after types. It’s famous for its rich colors, clarity, and the wide range of preserved inclusions it contains.
Dominican Amber: Found in the Dominican Republic and surrounding areas, Dominican amber is known for its wide array of colors and inclusions. It tends to be more transparent than Baltic amber and can range from pale yellow to deep red.
Succinite: A term often used to refer to Baltic amber due to its scientific name, Succinum. It’s derived from the Latin word for amber, “succinum.”
Burmite: Hailing from Myanmar (Burma), Burmite is amber from the Cretaceous period, known for its ancient inclusions. It can have a wide range of colors and is sometimes cloudy due to its geological age.
Mexican Amber: This amber comes from Mexico, particularly the Chiapas region. It can vary in color from pale yellow to deep red and often contains a diversity of inclusions.

Variations in Color, Transparency, and Inclusions:

Amber displays a captivating range of variations:

Color: Amber can exhibit various colors, including shades of yellow, orange, red, brown, and even rare greens and blues. The color is influenced by factors such as the resin’s original composition, the presence of impurities, and the conditions of fossilization.
Transparency: The transparency of amber can vary widely, from nearly opaque to highly transparent. This impacts how much light passes through the gemstone, affecting its visual appeal.
Inclusions: One of the most remarkable features of amber is the preserved organic inclusions trapped within it. These inclusions can include insects, plant fragments, air bubbles, and even small vertebrates. These trapped relics provide valuable insights into ancient ecosystems and life forms.

In conclusion, amber’s physical and chemical properties, along with its diverse types, colors, transparency levels, and inclusions, make it a truly unique gemstone that offers both aesthetic beauty and scientific significance.

Amber as a Gemstone

Amber holds a special place in the world of gemstones due to its organic origin, unique properties, and historical significance. While not a mineral like many other gemstones, its beauty and the captivating inclusions it can contain make it highly desirable for jewelry and decorative purposes.

Value Factors for Amber as a Gemstone:

The value of amber as a gemstone is influenced by several factors:

Color: Color is a primary determinant of amber’s value. Clear, vibrant, and rich colors, such as deep oranges, reds, and yellows, are highly prized. Rarer colors, like green and blue, are even more valuable.
Clarity: Clarity refers to the degree of transparency and the absence of significant internal flaws or fractures. Clear, transparent amber with minimal internal inclusions commands higher prices.
Size: Larger pieces of amber are generally more valuable, as they provide more material for crafting jewelry and allow the inclusions to be better observed.
Inclusions: While inclusions are often considered flaws in other gemstones, in amber, they can greatly enhance its value. The presence of well-preserved and interesting inclusions, such as insects or plant fragments, adds to the uniqueness and desirability of the gem.
Color Variation: Amber with multiple colors or color zones can be particularly sought after. This “sunburst” effect, where the colors radiate from a central point, can enhance its visual appeal.

Cutting, Polishing, and Jewelry Settings:

The process of crafting amber into jewelry involves several steps:

Cutting: Amber is relatively soft compared to other gemstones, so it can be easily cut and shaped. Skilled artisans cut raw amber pieces into various shapes such as cabochons, beads, pendants, and even intricately carved figurines.
Polishing: After cutting, amber is polished to enhance its luster and translucency. Polishing brings out its natural shine, giving it a smooth and glossy appearance.
Setting: Amber is often set in jewelry using traditional metal settings like sterling silver, gold, or even more contemporary materials. Bezel settings, which encircle the gem with a metal rim, are common for amber jewelry, as they offer protection and highlight the gem’s beauty.
Design: Amber’s warm and earthy tones make it suitable for various jewelry styles, from traditional to modern. It’s used in rings, necklaces, bracelets, earrings, and even more elaborate statement pieces.
Inclusion Display: In jewelry, craftsmen often design settings to showcase amber’s inclusions. Insects or other inclusions trapped within the gem can become central focal points of a piece, creating a unique and storytelling jewelry item.
Enhancements: Amber is typically not treated or enhanced, as its natural beauty and historical significance are its main attractions.

In conclusion, amber’s status as a gemstone is distinguished by its natural origin, captivating inclusions, and historical allure. The value of amber is influenced by color, clarity, size, and the uniqueness of its inclusions. Its versatile use in jewelry and the craftsmanship involved in cutting, polishing, and setting ensure that amber remains a cherished and timeless gemstone choice.

Occurrence and Locations

Amber is found in various regions around the world, with different deposits offering unique qualities and characteristics. Here are some of the notable geographic locations where amber is found:

Baltic Region (Northern Europe): The Baltic Sea area, encompassing countries like Poland, Russia, Lithuania, Latvia, and Estonia, is renowned for its Baltic amber. This amber is primarily from the Eocene epoch and is highly valued for its range of colors, transparency, and the exceptional preservation of inclusions, including insects and plant matter.
Dominican Republic: The Dominican Republic and neighboring Caribbean countries are known for their deposits of Dominican amber. This amber is more diverse in color than Baltic amber and often contains a wide array of inclusions, showcasing ancient ecosystems and flora.
Mexico (Chiapas): The Chiapas region in southern Mexico is a significant source of Mexican amber. This amber can vary in color from pale yellow to deep red and can contain intriguing inclusions. It’s often used in jewelry and artistic carvings.
Myanmar (Burma): Burmite, amber from Myanmar, is of Cretaceous age, making it some of the oldest known amber. It’s known for its ancient inclusions and can be cloudy due to its geological age.
Canada: Amber deposits have also been discovered in Canada, particularly in the province of Alberta. This amber is known for preserving a variety of prehistoric insects and plant matter.
Ukraine: Amber deposits are found in the Rivne region of Ukraine. Ukrainian amber, like Baltic amber, dates back to the Eocene epoch and is valued for its quality and preservation of inclusions.
Italy: The Sicilian amber, found in Italy, dates back to the Miocene epoch and is known for its unique blue color due to the presence of anthracene.
Lebanon: Lebanese amber, also from the Cretaceous period, is another ancient source. It is valued for its well-preserved inclusions and is considered among the oldest ambers.
Indonesia: Amber deposits have been found in Indonesia, including Sumatra and Borneo. Indonesian amber, also known as Borneo amber, is relatively less studied compared to other deposits.
New Zealand: A rare type of amber known as kauri gum is found in New Zealand. Kauri gum is derived from the resin of kauri trees and is valued for its use in jewelry and decorative objects.

These are just a few examples of the geographic locations where amber is found. Each deposit has its own geological history, unique characteristics, and inclusions that provide insights into the ancient world and ecosystems. Amber’s global presence has contributed to its rich cultural, scientific, and commercial significance.

Aragonite

Aragonite is a carbonate mineral and its formula is calcium carbonate. It has the same formula as Calcite and Vaterite, but has a different crystal structure. They are tabular, prismatic or needle-like, often with steep pyramidal or chisel-shaped ends, and can form columnar or spreading aggregates. Multiple twin crystals that appear hexagonal in shape are common. Although aragonite sometimes resembles calcite, it is easily distinguished by the absence of rhombic cleavage. Samples can be white, colorless, gray, yellowish, green, blue, reddish, purple or brown. Aragonite is found in oxidized areas of ore deposits and in evaporites, hot spring deposits and caves. It is also found in some metamorphic and igneous rocks and is formed by biological and physical processes, including precipitation from marine and freshwater environments.

Name: For its first-noted occurrence in the Aragon region, Spain

Association: For its first-noted occurrence in the Aragon region, Spain

Polymorphism & Series: Trimorphous with calcite and vaterite

Mineral Group: Aragonite group

Contents

Chemical Properties
Aragonite Physical Properties
Aragonite Optical Properties
Aragonite Occurrence
Uses of Aragonite
Distribution

Chemical Properties

Formula	CaCO₃
Common Impurities	Sr,Pb,Zn

Aragonite Physical Properties

Crystal habit	Orthorhombic
Color	Colorless to white or grey, often stained various hues by impurities, such as blue, green, red or violet; colourless in transmitted light.
Streak	Uncolored/white.
Luster	Vitreous, Resinous
Cleavage	Distinct/Good On {010} distinct; On {110} and {011} very indistinct.
Diaphaneity	Transparent, Translucent
Mohs Hardness	3½ – 4
Tenacity	Brittle
Density	2.947
Fracture	Sub-Conchoidal

Aragonite Optical Properties

Type	Biaxial (-)
2V:	Measured: 18° to 19°, Calculated: 16° to 18°
RI values:	nα = 1.529 – 1.530 nβ = 1.680 – 1.682 nγ = 1.685 – 1.686
Twinning	Single crystals are typically twinned cyclically on {110} producing pseudo-hexagonal aggregates of contact and penetration twins. Polysynthetic twinning produces lamellae or fine striations parallel to [100].
Optic Sign	Biaxial (-)
Birefringence	δ = 0.156
Relief	High
Dispersion:	weak

Aragonite Occurrence

It turns into calcite over geological time. Primary sediment in warm marine waters such as oolites and carbonate mud, an essential clastic sedimentary component as the hard parts of the shells and skeletons of many marine micro-organisms; also from evaporite deposits; in sinter in hot springs and in stalactite in caves; characteristic of high pressure, low temperature (blueschist facies) metamorphism; as amygdullary in basalt and andesite; It is a secondary component in altered ultramafic rocks.

Aragonite is a high pressure polymorph of calcium carbonate. Therefore, it occurs in high pressure metamorphic rocks such as those formed in subduction zones.

Aragonite is metastable at low pressures near the Earth’s surface and is therefore often replaced by calcite in fossils. Aragonite older than the Carboniferous is essentially unknown. It can also be synthesized by adding a solution of calcium chloride in water-ethanol mixtures at ambient temperatures or to a sodium carbonate solution at temperatures above 60 °C (140 °F).

Uses of Aragonite

Aragonite provides essential materials for marine life and also keeps the pH of the water close to its natural level to prevent the dissolution of biogenic calcium carbonate.

Aragonite has been successfully tested for the removal of contaminants such as zinc, cobalt and lead from contaminated wastewater.

Claims that magnetic water treatment can reduce calcification by converting calcite to aragonite have been met with skepticism, but remain under investigation.

Distribution

Many localities, but fine crystals are uncommon.

From Molina, Guadalajara Province, Spain.
Fine crystals from Racalmuto, Cianciana, and Agrigento, Sicily, Italy.
At Dogn´acska and Spania Dolina (Herrengrund), Slovakia.
From Tarnowitz, Silesia, Poland.
At ˇ the Erzberg, near Eisenerz, Styria, and from Leogang, Salzburg, Austria.
On the Spitzberg, Hoˇrenz, near B´ılina, Czech Republic.
From Frizington and Cleator Moor, Cumbria, England.
Fine examples at the Touissit mine, near Oujda, and from Tazouta, near Sefrou, Morocco.
Large crystals from Tsumeb, Namibia.
In the USA, in caves at Bisbee, Cochise Co., Arizona; large crystals from near Lake Arthur, Chavez Co., also near Santa Rosa, Guadalupe Co., New Mexico; in the Passaic mine, Sterling Hill, Ogdensburg, Sussex Co., New Jersey

Pearl

Pearls, often referred to as “gems of the sea,” are unique and exquisite organic gemstones that have captivated humanity for centuries. Their iridescent luster and timeless elegance have made them a symbol of beauty, wealth, and sophistication across cultures. Formed within the depths of certain mollusks, pearls are a result of nature’s meticulous craftsmanship.

Pearls are spherical or irregularly shaped objects formed within the soft tissue of certain mollusks, primarily oysters and mussels. These gemstones are composed of layers of calcium carbonate crystals known as aragonite, along with a protein called conchiolin. The interaction between these elements, along with environmental factors, contributes to the pearl’s unique visual characteristics.

Brief Overview of Pearl Formation

The fascinating process of pearl formation begins when an irritant, such as a grain of sand or a parasite, enters the soft tissues of a mollusk. In response to this intrusion, the mollusk’s defense mechanism is triggered. It secretes layers of nacre, a combination of aragonite and conchiolin, around the irritant. This process continues over time, with successive layers being deposited, creating a luminous and iridescent pearl.

There are two main types of pearls: natural pearls and cultured pearls. Natural pearls form when the irritant enters the mollusk naturally, without any human intervention. Cultured pearls, on the other hand, are formed through a controlled process initiated by humans. In cultured pearl farming, a nucleus made from mussel shell or a mother-of-pearl bead is introduced into the mollusk’s tissue, kickstarting the nacre deposition process.

The factors influencing a pearl’s quality and value include its size, shape, color, luster (the way it reflects light), and surface quality. Pearls can range in color from creamy white to shades of pink, blue, green, and even black. The overall appeal of a pearl is the result of these unique combinations of characteristics.

Pearls have held a significant place in human culture throughout history, symbolizing purity, wisdom, and luxury. From ancient civilizations to modern fashion runways, pearls continue to evoke a sense of elegance and grace, making them a cherished treasure both in the natural world and in the realm of human adornment.

Contents

Pearl Formation
Types of Pearls
Pearl Jewelry
Famous Pearls
Physical Properties
Occurrence
Pearl Types and Locations

Pearl Formation

Pearls are formed through a natural biological process within certain species of mollusks, primarily oysters and mussels. The process begins when an irritant, such as a grain of sand or a parasite, enters the soft tissue of the mollusk. In response to this foreign object, the mollusk’s defense mechanism is triggered. The mollusk secretes a substance called nacre, also known as mother-of-pearl, which is composed of alternating layers of aragonite (a crystalline form of calcium carbonate) and conchiolin (an organic protein).

Over time, the mollusk continues to deposit layers of nacre onto the irritant. These layers build up and eventually form a pearl. The lustrous surface of the pearl is created by the way light interacts with the layers of nacre, resulting in the characteristic iridescent sheen that pearls are known for.

Natural vs. Cultured Pearls

Natural Pearls: Natural pearls are formed entirely by natural processes without any human intervention. They are quite rare and are the result of a chance occurrence of an irritant entering the mollusk. The process of forming a natural pearl can take several years or even decades, and the outcome is often unpredictable in terms of size, shape, and quality.
Cultured Pearls: Cultured pearls are created through a process that involves human intervention. In pearl farming, a small nucleus, typically a piece of mussel shell or a mother-of-pearl bead, is carefully inserted into the mollusk’s tissue. This irritant serves as a nucleus around which the mollusk deposits layers of nacre, simulating the natural pearl formation process. The controlled environment of pearl farming allows for more predictable results in terms of pearl size, shape, and quality.

Oyster Anatomy and Pearl Formation Process

The anatomy of oysters and other mollusks plays a crucial role in the formation of pearls. Here’s an overview of the process within an oyster:

Mantle Tissue: The mantle is a specialized tissue within the oyster that plays a key role in pearl formation. It secretes both the nacre and the conchiolin, the two main components of pearls.
Irritant Intrusion: When an irritant, such as a grain of sand, enters the oyster’s soft tissue, it becomes lodged between the mantle and the shell. In response to this irritant, the mantle begins to secrete layers of nacre to coat and isolate the irritant.
Nacre Deposition: The oyster continues to deposit layers of nacre onto the irritant over time. This layering process is what creates the pearl’s structure and iridescent appearance.
Pearl Growth: As more layers of nacre are deposited, the pearl grows in size. The size and shape of the pearl are influenced by factors such as the shape of the irritant and the oyster’s unique biology.
Harvesting: In pearl farming, cultured pearls are harvested once they have reached the desired size and quality. The oysters are carefully opened, and the pearls are removed. The oysters can be returned to the water to potentially produce more pearls in the future.

Understanding the intricate relationship between mollusks, their anatomy, and the process of nacre secretion provides insight into the captivating journey that results in the creation of these stunning gemstones.

Types of Pearls

There are several types of pearls, each with its own unique characteristics, colors, and origins. Here’s an overview of some of the most well-known types of pearls:

Freshwater Pearls: These pearls are cultivated in freshwater mussels. They are usually produced in various shapes, including round, oval, and irregular. Freshwater pearls are known for their wide range of colors, from white and pink to lavender and even metallic hues. They are often more affordable compared to other types of pearls.
Akoya Pearls: Akoya pearls are cultured in saltwater oysters, primarily in Japan and China. They are prized for their classic round shape, high luster, and smooth surface. Akoya pearls are traditionally white or cream-colored, with overtones of pink or silver.
South Sea Pearls: These pearls are produced by Pinctada maxima, the largest and rarest species of oysters. South Sea pearls are typically larger in size compared to other pearls, and they are known for their satin-like luster. They come in shades of white, silver, and gold.
Tahitian Pearls: Also known as black pearls, Tahitian pearls are cultured in black-lipped oysters in French Polynesia. Despite their name, they come in a wide range of dark colors, including black, gray, green, and peacock. Their unique colors and overtones make them highly sought after.
Baroque Pearls: Baroque pearls have irregular, non-symmetrical shapes, which can vary from coin-shaped to elongated or abstract forms. They come in both freshwater and saltwater varieties and are often used in creative and artistic jewelry designs.
Keshi Pearls: Keshi pearls are non-nucleated pearls, meaning they form without a nucleus in the pearl sac. They can be found in both saltwater and freshwater mollusks. Keshi pearls are typically small and come in various shapes and colors. They are known for their natural and organic appearance.
Mabe Pearls: Also called blister pearls, mabe pearls are cultivated by attaching a nucleus to the inner shell of an oyster rather than embedding it within the soft tissue. This results in a flat-backed pearl that is often used in earrings, pendants, and rings.
Biwa Pearls: Historically, Biwa pearls referred to freshwater pearls produced in Lake Biwa in Japan. While the original Biwa pearls are no longer produced due to environmental changes, the term is still used to describe certain high-quality freshwater pearls.
Fireball Pearls: These pearls, often found in the South Sea and Tahitian varieties, are characterized by their intense and vibrant colors. The term “fireball” refers to their brilliant and fiery appearance.

These are just a few examples of the diverse types of pearls that exist. Each type has its own unique appeal, making pearls a versatile and captivating choice for jewelry and adornment.

Pearl Jewelry

Pearl jewelry has been treasured for its timeless beauty and elegance for centuries. From classic pearl strands to modern and innovative designs, pearls are used in various forms to create stunning jewelry pieces. Here are some popular types of pearl jewelry:

Pearl Necklaces: Pearl necklaces are perhaps the most iconic and traditional use of pearls in jewelry. They come in different lengths and styles, such as choker, princess, matinee, and opera lengths. A single strand of pearls, often with a simple clasp, is a staple in many jewelry collections.
Pearl Earrings: Pearl earrings are available in various styles, including studs, dangles, and hoops. They can feature different pearl types, sizes, and colors, allowing for versatility in matching different outfits and occasions.
Pearl Bracelets: Pearl bracelets add a touch of sophistication to the wrist. They can be made from various pearl types and strung on silk, wire, or elastic cord. Some designs incorporate multiple strands of pearls or combine pearls with other gemstones.
Pearl Rings: Pearl rings can be both elegant and contemporary. They come in solitaire designs, clusters, and settings that incorporate diamonds or other gemstones. Pearl engagement rings are also becoming a unique choice for those seeking an alternative to traditional diamond rings.
Pearl Pendants: Pearl pendants feature a single pearl or a cluster of pearls suspended from a chain. They can be simple and minimalist or elaborate and ornate, depending on the design.
Pearl Brooches: Pearl brooches add a touch of vintage charm and sophistication to clothing. They can feature pearls of various sizes and styles, often combined with other decorative elements.
Pearl Tiara and Hair Accessories: Pearls are used to create delicate tiaras, hairpins, and combs for special occasions like weddings and formal events. These accessories add a touch of elegance to hairstyles.
Pearl Statement Pieces: Contemporary jewelry designers often create unique and artistic statement pieces using pearls. These can include asymmetrical designs, mixed-media combinations, and avant-garde concepts that showcase pearls in unconventional ways.
Pearl Body Jewelry: Pearls can also be incorporated into body jewelry such as belly button rings, anklets, and toe rings, adding a touch of refinement to body adornment.
Matching Sets: Many jewelry sets include coordinated pieces like necklaces, earrings, and bracelets that feature matching pearls, creating a harmonious look.

Pearls are versatile and can be combined with various metals, gemstones, and materials to create pieces that range from traditional to contemporary. Whether you’re looking for a timeless and elegant piece or a bold and innovative design, pearl jewelry offers a wide range of options to suit different styles and preferences.

Famous Pearls

Several famous pearls have gained worldwide recognition due to their size, color, history, and the stories behind them. Here are a few examples of famous pearls:

La Peregrina Pearl: One of the most famous pearls in history, La Peregrina, was discovered in the 16th century off the coast of Panama. Its name means “The Pilgrim” in Spanish. The pearl’s unique pear shape and size (approximately 50.56 carats) have made it a coveted gem for centuries. It has passed through the hands of various monarchs and celebrities, including Queen Mary I of England and Richard Burton, who famously gifted it to Elizabeth Taylor as a Valentine’s Day present.
Hope Pearl: The Hope Pearl is a large, natural pearl that measures around 1.7 inches in length. It was once part of the collection of Henry Philip Hope, a gem collector in the early 19th century. The pearl has a remarkable blue-gray color and is often displayed alongside the Hope Diamond in museums due to their similar names and historical connections.
La Regente Pearl: Also known as the “Regent Pearl,” this perfectly symmetrical, white, and nearly round pearl weighs around 140.5 grains (about 35 carats). It was discovered in the Gulf of Panama in the 16th century. The pearl got its name from the French Regent, Philippe II, Duke of Orleans, who owned it in the 18th century.
The Queen’s Pearls: Queen Mary II of England possessed an extensive collection of pearls, including a five-strand pearl necklace. The necklace, which has become iconic, was featured in many of her portraits. The Queen’s Pearls have remained a symbol of royal elegance and sophistication.
Arco Valley Pearl: Discovered in 1982, the Arco Valley Pearl is one of the largest freshwater pearls ever found. It weighs approximately 575 carats and measures over 2 inches in diameter. Its unusual size and shape have contributed to its fame.
Peregrina Pearl (Revisited): In addition to the historic La Peregrina Pearl, a replica of the original was created in 2011. This replica, known as “La Peregrina II,” was made using a silicone mold of the original pearl. It was commissioned by Elizabeth Taylor’s estate after the original pearl was sold at auction.
Ducal Pearl Necklace: This necklace, part of the British royal jewelry collection, features a large baroque pearl pendant suspended from a diamond necklace. The pearl is believed to have belonged to Queen Mary I of England and was passed down through generations.

These famous pearls have captured the imagination of people around the world and continue to be admired for their beauty, history, and the stories they tell.

Physical Properties

Pearls are not only prized for their beauty but also for their unique physical properties. Here are some key physical properties of pearls:

Luster: Luster refers to the way light interacts with the surface of a pearl. Pearls are known for their exquisite luster, which gives them a soft, glowing appearance. The iridescence comes from the overlapping layers of nacre, which refract and reflect light, creating a shimmering effect.
Color: Pearls come in a wide range of colors, from classic white and cream to shades of pink, lavender, gray, black, and even rare and exotic colors like golden and peacock. The color of a pearl is influenced by the type of mollusk, the water it’s cultivated in, and other environmental factors.
Size: Pearls can vary greatly in size, from tiny seed pearls to larger pearls that are several centimeters in diameter. The size of a pearl is determined by factors such as the size of the irritant, the mollusk’s biology, and the length of time the pearl is allowed to grow.
Shape: Pearls come in various shapes, including round, oval, button, drop, baroque (irregular), and circled (with rings around the surface). The round shape is particularly prized and considered the classic pearl shape.
Surface Quality: The surface of a pearl can have various imperfections, including blemishes, spots, and irregularities. Pearls with smoother surfaces are typically more valuable. However, some types of pearls, such as baroque pearls, embrace their unique surface characteristics.
Nacre Thickness: The thickness of the nacre layers is a crucial factor in determining the quality and durability of a pearl. Thicker nacre generally leads to stronger pearls with better luster.
Density and Hardness: Pearls are relatively soft compared to other gemstones, with a hardness of 2.5 to 4.5 on the Mohs scale. This makes them more susceptible to scratches and damage. Their density varies depending on the type of pearl.
Translucency: High-quality pearls often have a degree of translucency, allowing some light to pass through the layers of nacre. This property contributes to the pearl’s overall radiance.
Weight: The weight of a pearl is typically measured in carats (the same unit used for diamonds and other gemstones). The weight is influenced by the pearl’s size, density, and type.
Fluorescence: Some pearls may exhibit fluorescence under certain lighting conditions. This can add a unique dimension to their appearance, especially in pearls with darker colors.

Understanding these physical properties can help both consumers and collectors appreciate the distinctiveness and value of different types of pearls. The interplay of these properties contributes to the allure and charm of pearls as treasured gemstones.

Occurrence

Pearls are formed naturally within certain species of mollusks, including oysters and mussels. The occurrence of pearls involves specific conditions and factors that contribute to their formation. Here’s an overview of how pearls occur:

Mollusk Habitat: Mollusks that produce pearls inhabit various aquatic environments, including oceans, seas, rivers, and freshwater bodies. Different types of mollusks thrive in different habitats, and the conditions of their environment play a significant role in pearl formation.
Irritant Intrusion: The pearl formation process begins when an irritant, such as a grain of sand, a parasite, or another foreign object, enters the soft tissue of a mollusk. This irritant becomes lodged within the mantle tissue of the mollusk.
Nacre Secretion: In response to the irritant, the mollusk’s mantle tissue starts secreting nacre, a combination of aragonite (calcium carbonate) and conchiolin (an organic protein). The nacre is gradually deposited in layers around the irritant. This layering process is what ultimately forms the pearl.
Layering Over Time: Over time, the mollusk continues to deposit layers of nacre onto the irritant. These layers build up, gradually forming the pearl’s size and shape. The time required for a pearl to form can vary greatly, ranging from several months to several years.
Natural and Cultured Pearls: Pearls can occur naturally when the irritant enters the mollusk without human intervention. These are referred to as natural pearls and are quite rare. In contrast, cultured pearls are formed through a controlled process initiated by humans. In pearl farming, a nucleus is intentionally introduced into the mollusk’s tissue to stimulate nacre deposition.
Pearl Types and Locations: Different types of pearls are associated with specific mollusk species and geographic regions. For example, Akoya pearls are primarily cultivated in Japan and China, while South Sea pearls are found in the waters of the South Pacific. Freshwater pearls are cultivated in various freshwater bodies around the world.
Environmental Factors: The quality and characteristics of pearls are influenced by environmental factors such as water temperature, water quality, and the mollusk’s diet. These factors affect the growth rate, size, color, and luster of the pearls.
Harvesting: In the case of cultured pearls, once the pearls have reached the desired size and quality, they are harvested by carefully opening the mollusks. The pearls are then removed, and the mollusks can be returned to the water to potentially produce more pearls in the future.

Overall, the occurrence of pearls is a fascinating natural process that involves the intricate interaction between mollusks, their environment, and the specific conditions that lead to the formation of these exquisite gemstones.

Pearl Types and Locations

Pearls come in various types, each associated with specific mollusk species and geographic regions. Different types of pearls are cultivated in various parts of the world, and their unique characteristics make them highly valued in the world of jewelry and adornment. Here’s a breakdown of some pearl types and their locations:

Akoya Pearls:
- Type: Saltwater pearl
- Location: Primarily cultivated in Japan and China, with Japanese Akoya pearls being particularly renowned. They are also produced in other regions with suitable conditions.
- Characteristics: Known for their classic round shape, high luster, and smooth surface. They are often white or cream-colored, with overtones of pink or silver.
South Sea Pearls:
- Type: Saltwater pearl
- Location: Cultivated in the warm waters of the South Pacific, including countries like Australia, Indonesia, the Philippines, and Myanmar (Burma).
- Characteristics: Larger in size compared to other pearls, with a satin-like luster. They come in shades of white, silver, and gold.
Tahitian Pearls:
- Type: Saltwater pearl
- Location: Cultured in black-lipped oysters primarily in French Polynesia, including the islands of Tahiti.
- Characteristics: Known for their unique dark colors, ranging from black and gray to green, peacock, and iridescent overtones.
Freshwater Pearls:
- Type: Freshwater pearl
- Location: Cultivated in various freshwater bodies, including lakes, rivers, and ponds, around the world. China is a major producer of freshwater pearls.
- Characteristics: Come in various shapes, sizes, and colors, including white, pink, lavender, and metallic hues. Often more affordable than saltwater pearls.
Biwa Pearls:
- Type: Freshwater pearl
- Location: Originally cultivated in Lake Biwa in Japan. While the original Biwa pearls are no longer produced due to environmental changes, the term is still used to describe certain high-quality freshwater pearls.
Mabe Pearls:
- Type: Saltwater or freshwater pearl (depending on origin)
- Location: Cultivated in various regions, including Japan, Indonesia, and Australia.
- Characteristics: These pearls are blister pearls, often flat on one side due to their attachment to the shell. They are used in jewelry pieces like earrings and pendants.
Keshi Pearls:
- Type: Can be either saltwater or freshwater pearls (depending on origin)
- Location: Cultivated in both saltwater and freshwater mollusks.
- Characteristics: Small, irregularly shaped pearls that form without a nucleus. They come in various colors and are often used in artistic and creative jewelry designs.

These are just a few examples of the many pearl types found around the world. Each type has its own distinct characteristics and beauty, making pearls a diverse and captivating choice for jewelry enthusiasts and collectors.

Coral

Coral is a marine animal that belongs to the class Anthozoa and the phylum Cnidaria. It is composed of small, soft-bodied animals called polyps that secrete a hard, calcium carbonate skeleton. Coral is found in warm, shallow waters around the world, and is known for its bright, vibrant colors and unique patterns. While coral is not considered a mineral, it has been used for decorative and ornamental purposes for centuries, and is often classified as a precious or semi-precious gemstone. Coral jewelry and ornaments are popular in many cultures, and are often associated with good luck, protection, and healing properties. However, the harvesting of coral for commercial purposes has had a significant impact on coral populations around the world, and many species are now considered endangered or threatened due to overexploitation and habitat loss.

According to Greek legends, coral is the blood spilled by the hero Perseus when he cut off the head of the monster Medusa. In fact, coral is skeletal material produced by marine animals. Coral is organic and created by living organisms. When coral polyps die, the hardened skeleton remains and this material is used as a gemstone. Most corals are white, but nature can create coral in many other colors, including the popular orange to red forms. Usually its compound is calcium carbonate. Corals have a dull appearance when collected and are then polished. Precious corals, which are red and pink in color, are found around Japan and Malaysia in African coastal waters and the Mediterranean. Black corals are mined from around the West Indies, Australia and Pacific Islands.

Coral is a gemstone that has been used for thousands of years. Besides the beautiful solid colors found in Coral, there may also be color zones or swirls where white, pink, orange and red are most common.

Coral gemstones can be solid or porous depending on polyp formation. Despite Coral’s beautiful colors, it is very soft and brittle and does not make a durable gemstone. It is prone to both scratching and chipping.

Mineral Group: Organic Minerals

Mineralogy: Mostly calcium carbonate (CaCO₃)

Environment: Corals are primitive animals belonging to the Phylum Coelenterata or Cnidaria and are found anywhere in the world’s ocean at depths ranging from the tidal mark to the abyss, up to 6000 m.

Contents

Coral Varieties
Geological formation of coral
Coral reefs and their importance
Physical Properties
Uses of coral
References

Coral Varieties

Black Coral: Black colored marine coral species from the Antipatharia family.
Precious Coral: Also known as Red Coral. Precious Coral has a natural pink to red color and is Coral’s most desirable form of jewellery.
Red Coral: The marine coral species corallium rubrum (or several related species) with a natural color from light pink to deep red.

Geological formation of coral

Coral is formed by small animals known as coral polyps, which belong to the class Anthozoa of the phylum Cnidaria. These tiny organisms secrete a hard, calcareous skeleton made of calcium carbonate that serves as their protective home. Over time, as individual polyps die and new ones take their place, the calcareous skeleton grows and forms large, complex structures known as coral reefs.

Coral reefs are typically found in warm, shallow waters in tropical and subtropical regions around the world. They are formed by the accumulation of coral skeletons and other calcareous material over many thousands of years. The growth rate of coral reefs can vary depending on environmental factors such as water temperature, water quality, and the availability of nutrients.

Coral reefs play an important role in the marine ecosystem, providing habitat and shelter for a wide variety of marine life, including fish, crustaceans, and other invertebrates. They also protect coastlines from erosion and storm damage, and are a popular destination for tourism and recreation. However, coral reefs are under threat from a range of factors, including climate change, pollution, overfishing, and habitat destruction.

Coral reefs and their importance

Coral reefs are incredibly important ecosystems that support a vast array of marine life, including fish, invertebrates, and other organisms. They also provide a range of valuable ecological services, such as shoreline protection, nutrient cycling, and carbon sequestration. Here are some of the key reasons why coral reefs are important:

Biodiversity: Coral reefs are one of the most diverse ecosystems on Earth, supporting an estimated 25% of all marine species, despite covering less than 1% of the ocean floor. Many of these species are dependent on coral reefs for their survival, including commercially important fish and shellfish.
Fisheries: Coral reefs provide a critical source of food and income for millions of people around the world. They support some of the world’s most important fisheries, including those for tuna, snapper, and grouper, as well as for many types of shellfish.
Coastal protection: Coral reefs act as natural breakwaters, protecting coastlines from storm surges, waves, and erosion. This is particularly important in areas where sea level rise and increased storm frequency and intensity due to climate change are becoming more common.
Tourism: Coral reefs are a major attraction for tourists, generating billions of dollars in revenue each year. They are particularly popular for activities such as snorkeling and scuba diving, and their beauty and diversity are a major draw for travelers.
Climate regulation: Coral reefs play an important role in regulating the Earth’s climate by absorbing and storing large amounts of carbon dioxide from the atmosphere. This helps to mitigate the impacts of climate change and ocean acidification.

Overall, coral reefs are a vital part of the marine ecosystem and provide a wide range of benefits to human societies. Protecting and preserving these ecosystems is essential for the health and well-being of both marine and human communities around the world.

Physical Properties

Coral is a marine organism that belongs to the family of Anthozoa, and it has certain physical properties that distinguish it from other gemstones. Here are some of the physical properties of coral:

Hardness: Coral has a hardness of 3.5 on the Mohs scale, which makes it relatively soft compared to other gemstones. As a result, it can be easily scratched or damaged, and it requires special care when cleaning or handling.
Density: The density of coral ranges from 1.5 to 1.7 g/cm³, which makes it fairly lightweight compared to other gemstones. This makes it comfortable to wear as jewelry, but it also makes it susceptible to damage from impacts or pressure.
Color: Coral can come in a wide range of colors, including white, pink, red, orange, and black. The color of coral is determined by the presence of pigments and other organic compounds, as well as by the species of coral from which it is derived.
Luster: Coral has a dull to waxy luster, which is characteristic of organic materials. This is different from the glassy or metallic luster of many other gemstones.
Transparency: Coral is opaque, which means that light cannot pass through it. This is because it is made up of numerous small calcium carbonate structures called polyps, which are densely packed together.
Refractive index: The refractive index of coral ranges from 1.486 to 1.658, depending on the species and color of the coral. This determines how light is bent and reflected within the gemstone, and can affect its appearance and beauty.

Overall, coral is a unique and beautiful gemstone that has its own distinct physical properties. Its softness and susceptibility to damage make it important to handle with care, but its beauty and cultural significance make it a popular choice for jewelry and decorative objects.

Uses of coral

Coral has been used for a wide range of purposes throughout human history, from decorative objects to medicinal remedies. Here are some of the most common uses of coral:

Jewelry: Coral is a popular choice for jewelry, particularly in traditional and ethnic designs. It is often carved into beads, pendants, and other shapes, and can be combined with other gemstones and metals to create unique pieces.
Decorative objects: Coral has long been used to create decorative objects, such as sculptures, figurines, and ornaments. Its unique color and texture make it a popular choice for home decor and other decorative applications.
Feng shui: In the practice of feng shui, coral is believed to bring positive energy and luck into the home. It is often used in decor and jewelry to promote good fortune and prosperity.
Aquariums: Coral is also a popular choice for aquarium enthusiasts, as it can provide a natural and beautiful habitat for fish and other marine life.

It is worth noting that the use of coral for decorative purposes has led to overharvesting and damage to coral reefs. As such, it is important to ensure that any coral products you purchase are sustainably sourced and do not contribute to further harm to these fragile ecosystems.

References

Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
Gem notes: Gemstone Information. Fire Mountain Gems and Beads. (n.d.). Retrieved October 24, 2021, from https://www.firemountaingems.com/resources/encyclobeadia/gem-notes/gmstnprprtscrl1.
Minerals.net. 2021. Coral: The gemstone coral information and pictures. [online] Available at: <https://www.minerals.net/gemstone/coral_gemstone.aspx> [Accessed 24 October 2021].

The Cetina River Eye

This reservoir like eye is the source of the Cetina river in southern Croatia. It has a length of 101 km and also its basin covers an area of 1,463 km2. From its source, Cetina descends from an elevation of 385 metres above sea level to the Adriatic Sea. It is the most water-rich river in Dalmatia.

The eye of Cetina river in Croatia is more than 150 meters (490 feet) deep.

The source of the river is a karst spring.
Besides the Vismur basin, Cetina also receives a lot of water from the western Bosnian karst field via underground routes. Its lower route starts 20 kilometers (12 mi) from Omiš, near the village of Zadvarje, at an altitude of 49 meters (161 ft) above sea level from the Gubavica Waterfalls. Here it leaves its canyon and flows into a valley that still retains the appearance of a canyon.

The second part of Cetina and its relatively large drop in height was used to build several important hydroelectric power stations.

The total drainage area is around 12,000 km2 and the annual discharge is around 105 m3s-1 as a result of an average annual precipitation of 1380 mm.

Cetina River Canyon is also known as an important historical and archaeological site. Archaeologists have found axes from ancient times, the remains of weapons of Roman legionnaires, medieval tools, etc., around the river and in the bed of Cetina. they found it. The finds were items of historical importance.

Kaolinite

Kaolinite is a clay mineral with chemical composition Al2Si2O5(OH)4. It is an important industrial mineral. Rocks rich in kaolinite are called kaolin. Kaolinite, common group of clay minerals that are hydrated aluminum silicates; they contain the main components of kaolin (china clay). The group includes kaolinite, which is chemically similar but amorphous to kaolinite, and its rarer forms, stalagmite and nacrite, halloysite and allophane.

It is a layered silicate mineral with a tetrahedral silica layer (SiO4) bonded to an octahedral layer of alumina (AlO6) octahedra through oxygen atoms.

Kaolinite, nacrite, and dickite occur as compact or granular masses and mica-like clumps as small, sometimes elongated, hexagonal plates. Feldspars are natural change products of feldspathoids and other silicates. Anoxide, previously considered a kaolinite group mineral with a higher-than-normal silica-to-alumina ratio, is now considered kaolinite and free silica (mainly non-crystalline). For chemical formula and detailed physical properties

Kaolinite is the raw material of brick, pottery and tile.It has played a vital role in the development of human civilization.The most important of these minerals is kaolinite. Kaolinite It forms white, microscopic, pseudo-hexagonal plates.

compact or granular masses and mica-like clumps. Three other minerals – stalagmite, nacrite and halloysite – chemically identical to kaolinite, but monoclinic system. Four found together and often visually indistinguishable.

Kaolinite is a natural product of mica degradation. plagioclase and sodium-potassium feldspars under Effect of water, dissolved carbon dioxide and organic matter acids. Used in agriculture; as a filler in foods such as chocolate; mixed with pectin as an antidiarrheal; as paint expander; as a reinforcing agent in rubber; and as powder agent in foundry operations

Name: The name kaolin is derived from Gaoling. Chinese village near Jingdezhen in southeastern China’s Jiangxi Province. The name entered English in 1727 from the French version of the word: kaolin.

Kaolinite has low shrinkage-swelling capacity and low cation exchange capacity (1–15 meq/100 g). A soft, earthy, usually white mineral (dioctahedral phyllosilicate clay) produced by chemical weathering of aluminum silicate minerals such as feldspar. In many parts of the world it is pink-orange-red with iron oxide, giving it a distinctive rust color. Lighter concentrations give white, yellow or light orange colors. Alternating layers are sometimes found, as in Providence Canyon State Park in Georgia, United States. Commercial grades of kaolin are supplied and transported as dry powder, semi-dry noodles or liquid slurry.

Association: Quartz, feldspar, muscovite.

Polymorphism & Series: Dickite, halloysite, and nacrite are polymorphs

Mineral Group: Kaolinite-serpentine group.

Cell Data: Space Group: P1: a = 5.15 b = 8.95 c = 7.39 ® = 91:8 ± ¯ = 104:5 ±¡105:0 ± ° = 90 ± Z = [2]

X-ray Powder Pattern: Scalby, Yorkshire, England (1A). 7.16 (vvs), 3.573 (vvs), 4.336 (vs), 2.491 (s), 2.289 (s), 2.558 (ms), 2.379 (ms)

Contents

Chemical Properties
Kaolinite structure showing interlayer hydrogen bonds
Structural Transformations
Milling
Drying
Metakaolin
Physical Properties
Optical Properties
Occurrence
Uses Area
Safety
The Occupational Safety and Health
Geotechnical engineering
Distribution
References

Chemical Properties

Chemical Classification	Phyllosilicates Kaolinite-serpentine group
Formula	Al2Si2O5(OH)4
Common Impurities	Fe,Mg,Na,K,Ti,Ca,H2O

Kaolinite structure showing interlayer hydrogen bonds

Compared to other clay minerals, kaolinite is chemically and structurally simple. It is defined as a 1:1 or TO clay mineral because its crystals consist of stacked layers of RO. Each TO layer consists of a tetrahedral (T) sheet of silicon and oxygen ions bonded to an octahedral (O) sheet of oxygen, aluminum, and hydroxyl ions. The T layer is so named because each silicon ion is surrounded by four oxygen ions forming a tetrahedron. The O layer is so named because each aluminum ion is surrounded by six oxygen or hydroxyl ions arranged at the corners of an octahedron. The two layers in each layer are strongly bonded to each other via shared oxygen ions, while the layers are bonded via hydrogen bonding between the oxygen on the outer face of the T layer of one layer and the hydroxyl on the outer face of the O layer of the next layer.

Structural Transformations

Kaolinite group clays undergo a series of phase transformations after heat treatment in air at atmospheric pressure.

Milling

Grinding kaolinite results in the formation of a mechanochemically amorphous phase similar to metakaolin, although the properties of this solid are quite different. Great energy is required to convert kaolinite into metakaolin.

Drying

Below 100 °C (212 °F), exposure to dry air will slowly remove liquid water from the kaolin. The final state of this transformation is called “skin dryness”. Between 100 °C and about 550 °C (1,022 °F), the remaining liquid water is expelled from the kaolinite. The final state of this transformation is called “bone dryness”. Over this temperature range, the removal of water is reversible: if kaolin is exposed to liquid water, it will be reabsorbed and decomposed into fine particle form. Subsequent transformations represent irreversible and permanent chemical changes.

Metakaolin

Endothermic dehydration of kaolinite begins at 550-600 °C and produces disordered metakaolin, but continuous loss of hydroxyl is observed up to 900 °C (1,650 °F). Although historically there has been much disagreement about the nature of the metakaolin phase, extensive research has led to general consensus that metakaolin is not a simple mixture of amorphous silica (SiO2) and alumina (Al2O3), but rather a complex amorphous structure that retains some of it. longer range order (but certainly not crystalline) due to stacking of hexagonal layers.

Physical Properties

Crystal habit
Colour	White to cream and pale-yellow, also often stained various hues, tans and browns being common.
Streak	White, or paler than the sample.
Hardness	2 – 2½
Luster	Waxy, Pearly, Dull, Earthy
Cleavage	Perfect on {001}.
Diaphaneity	Translucent, Opaque
Crystal System	Triclinic
Tenacity	Flexible but inelastic
Density	2.63 g/cm3 (Calculated)
Fracture	Irregular/Uneven, Conchoidal, Sub-Conchoidal, Micaceous

Optical Properties

Type	Biaxial (-)
Color / Pleochroism	Transparent to translucent as single crystals
2V:	Measured: 24° to 50°, Calculated: 44°
RI values:	nα = 1.553 – 1.563 nβ = 1.559 – 1.569 nγ = 1.560 – 1.570
Birefringence	0.017
Relief	Low
Dispersion:	none

Occurrence

It replaces other aluminosilicate minerals during hydrothermal alteration and weathering. A common component from which the clay-size fraction of sediments can form by direct precipitation

Kaolinite is one of the most common minerals; As kaolin, it is mined in Malaysia, Pakistan, Vietnam, Brazil, Bulgaria, Bangladesh, France, United Kingdom, Iran, Germany, India, Australia, South Korea, People’s Republic of China, Czech Republic, Spain, South. Africa, Tanzania and the United States.

Kaolinitic saprolite mantles are common in Western and Northern Europe. The ages of these mantles are from Mesozoic to Early Cenozoic.

Kaolinite clay is abundant in soils formed by chemical erosion of rocks in hot and humid climates, such as tropical rainforests. When comparing soils along a slope towards increasingly cooler or drier climates, the proportion of kaolinite decreases while the proportion of other clay minerals such as illite (in colder climates) or smectite (in drier climates) increases. Such climatically relevant differences in clay mineral content are often used to reveal changes in climates in the geological past, where ancient soils were buried and preserved.

Uses Area

The main use of the mineral kaolinite (about 50% of the time) is in paper production; Its use provides shine on some coated paper types.
- in ceramics (main component of porcelain)
- in toothpaste
- as a light-emitting material in white incandescent bulbs
- in cosmetics
- In industrial insulation material called Kaowool (a type of mineral wool)
- in ‘pre-work’ skin protection and barrier creams
- in paint to prolong titanium dioxide white pigment and change gloss levels
- to change the properties of rubber upon vulcanization
- in adhesives to change the rheology
- as a spray applied to crops to prevent insect damage in organic farming and to prevent sunburn on apples
As a whitewash in traditional stone-walled houses in Nepal (most common method is to paint the top with white kaolin clay and the middle with red clay; the red clay can extend to the bottom or the bottom can be painted black)
As a filler or as a coating to improve the surface in papermaking, as a filler in Edison Diamond Discs Because kaolinite may contain very small traces of uranium and thorium, as an indicator in radiological dating, it was common to treat stomach upset (more recently, industrially produced preparations of kaolinite for the treatment of diarrhea), similar to what parrots (and later humans) originally used in South America.
for face masks or soap (known as “White Clay”) body wraps, spa body treatments like cocoons or just spot treatments like feet, back or hands. Essential oil can be added to add a pleasant aroma, or seaweed can be added to increase the nutritional values of the treat.
as an adsorbent in water and wastewater treatment to promote blood coagulation in diagnostic procedures, e.g. Kaolin clotting time
in the form of metakaolin modified as a pozzolan; When added to a concrete mix, metakaolin accelerates the hydration of Portland cement and takes part in the pozzolanic reaction with portlandite, which is formed in the hydration of the main cement minerals (e.g. alite).
in the form of modified metakaolin as a basic ingredient for geopolymer compounds

Safety

People can be exposed to kaolin in the workplace by breathing in the powder or from skin or eye contact.

The Occupational Safety and Health

The Occupational Safety and Health Administration (OSHA) has set the statutory limit (permissible exposure limit) for workplace kaolin exposure as 15 mg/m3 total exposure and 5 mg/m3 respiratory exposure in an 8-hour workday. The National Institute of Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) as 10 mg/m3 total exposure TWA 5 mg/m3 respiratory exposure during an 8-hour workday.

Geotechnical engineering

Araştırma sonuçları, kaolinitin jeoteknik mühendisliğinde kullanımının alternatif olarak, özellikle mevcudiyeti toplam kaya kütlesinin %10,8’inden az ise, daha güvenli illit ile değiştirilebileceğini göstermektedir.

Distribution

Pure material from many localities, including:

at Kauling, Kiangsi Province,China.
In numerous china-clay pits in Cornwall and Devon, England.
At Limoges, Haute-Vienne,France.
Near Dresden, Kemmlitz, and Zettlitz, Saxony, and elsewhere in Germany.
Large deposits in the Donets Basin, Ukraine.
In the USA, at Macon, Bibb Co., Georgia; at the Dixie Clay Company mine, and in the Lamar Pit, near Bath, Aikin Co., South Carolina; near Webster, Jackson Co., North Carolina; near Murfreesboro, Pike Co., and at Greenwood, Sebastian Co., Arkansas; from Mesa Alta, Rio Arriba Co., New Mexico.
At Huberdeau, Quebec, and near Walton, Nova Scotia, Canada

References

Britannica, T. Editors of Encyclopaedia (2018, January 25). Kaolinite. Encyclopedia Britannica. https://www.britannica.com/science/kaolinite
Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
Dana, J. D. (1864). Manual of Mineralogy… Wiley.
Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
Mindat.org. (2019): Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].
Smith.edu. (2019). Geosciences | Smith College. [online] Available at: https://www.smith.edu/academics/geosciences [Accessed 15 Mar. 2019].

Economically Important Metal Concentrations in Earth’s Crust

The Earth’s crust contains a wide range of metal concentrations, but not all of them are economically viable for extraction. The economic viability of metal concentrations in the Earth’s crust depends on several factors, including the abundance of the metal, its concentration in ores or minerals, the accessibility and cost of extraction, and the demand and market price for the metal. Here are some examples of economically important metal concentrations in the Earth’s crust:

Aluminum (Al): Aluminum is the most abundant metal in the Earth’s crust, comprising about 8% of the crust by weight. It is widely used in various industrial applications, including transportation, construction, packaging, and electrical transmission. Bauxite, a type of laterite deposit, is the main source of aluminum, with major deposits found in countries like Australia, Guinea, and Brazil.
Iron (Fe): Iron is a crucial metal used in the production of steel, which is used in infrastructure, machinery, and many other applications. Iron is abundant in the Earth’s crust, comprising about 5% of the crust by weight. Iron ore deposits are found in various forms, including hematite, magnetite, and taconite, with major deposits found in countries like Australia, Brazil, and China.
Copper (Cu): Copper is an essential metal used in various industries, including electrical wiring, plumbing, and electronics. Copper deposits can be found in a variety of geological settings, including porphyry deposits, sedimentary deposits, and volcanic-hosted massive sulfide deposits. Major copper deposits are found in countries like Chile, Peru, and the United States.
Gold (Au): Gold is a precious metal used in jewelry, electronics, and investment, and has been valued for its rarity and beauty for thousands of years. Gold deposits can occur in a variety of forms, including placer deposits, lode deposits, and epithermal deposits. Major gold-producing countries include China, Australia, and Russia.
Nickel (Ni): Nickel is a key metal used in the production of stainless steel, batteries, and other industrial applications. Nickel deposits can be found in various geological settings, including laterite deposits, sulfide deposits, and magmatic deposits. Major nickel deposits are found in countries like Indonesia, Russia, and Canada.
Zinc (Zn): Zinc is an important metal used in the production of galvanized steel, batteries, and other applications. Zinc deposits are typically found in sedimentary-hosted deposits, such as carbonate-hosted deposits and Mississippi Valley-type (MVT) deposits. Major zinc-producing countries include China, Australia, and Peru.
Lead (Pb): Lead is a versatile metal used in batteries, bullets, and other applications. Lead deposits are typically associated with zinc deposits and can be found in sedimentary-hosted deposits, such as MVT deposits and sedimentary exhalative (SEDEX) deposits. Major lead-producing countries include China, Australia, and the United States.
Tin (Sn): Tin is used in various applications, including electronics, packaging, and soldering. Tin deposits can occur in a variety of forms, including placer deposits, cassiterite-rich veins, and greisen deposits. Major tin-producing countries include China, Indonesia, and Myanmar.

These are just some examples of economically important metal concentrations in the Earth’s crust. There are many other metals and minerals that are economically valuable and used in a wide range of applications, depending on their availability, concentration, and demand in the global market. The extraction and utilization of these metal resources require careful consideration of economic, environmental, and social factors to ensure sustainable resource management.

Aluminum (8.13%)
Iron (5.00%)
Calcium (3.63%)
Sodium (2.83%)
Potassium (2.59%)
Magnesium (2.09%)
Titanium (0.57%)
Hydrogen (0.14%)
Manganese (0.10%)
Phosphorus (0.10%)

Other metals that are economically important include copper, gold, silver, lead, zinc, nickel, and platinum, among others. The concentration of these metals in the Earth’s crust is much lower than the most common metals, with copper being the most abundant at 0.0068%, followed by lead at 0.0013%, zinc at 0.0075%, and nickel at 0.0081%.

Here are some typical background and ore levels of several important metals:

Copper:

Background levels: 10-50 ppm
Ore levels: 0.5-5% Cu

Gold:

Background levels: 0.0005-0.5 ppm
Ore levels: 1-20 g/t Au

Silver:

Background levels: 0.01-1 ppm
Ore levels: 50-800 g/t Ag

Lead:

Background levels: 10-50 ppm
Ore levels: 3-10% Pb

Zinc:

Background levels: 10-150 ppm
Ore levels: 3-15% Zn

Nickel:

Background levels: 50-200 ppm
Ore levels: 0.5-3% Ni

It’s important to note that these levels can vary widely depending on the deposit and location.

Most valuable metal in Earth Crust

The most valuable metal in the Earth’s crust can vary depending on a number of factors such as current market demand, availability, and the cost of extraction. Precious metals, such as gold, platinum, and silver, have historically been highly valued due to their scarcity and unique properties, and are often associated with luxury items and financial instruments. Other metals, such as copper, nickel, and iron, are highly valued for their usefulness in industry and infrastructure, and are considered to be more economically important. However, it’s worth noting that the value of a metal depends not only on its physical properties, but also on the societal, cultural, and economic factors that influence its perceived value.

In terms of the most valuable metal by market price, the answer can vary over time depending on a number of factors, such as supply and demand, geopolitical events, and technological advances. However, historically, some of the most valuable metals in the Earth’s crust have included precious metals like gold, silver, and platinum, as well as rare earth metals like neodymium, yttrium, and cerium. These metals are used in a wide range of applications, including electronics, jewelry, and industrial processes, among others.

It’s worth noting that the value of a metal depends not only on its price but also on its availability, which is influenced by a number of geological, economic, and political factors. For example, a metal may have a high market price, but if it is only found in small quantities or in hard-to-reach locations, its actual value may be limited. Additionally, factors such as production costs, energy requirements, and environmental impact can all affect the overall economic viability of extracting and using a particular metal.

The percentage of valuable metals in the Earth’s crust varies widely, depending on the metal in question. Here are a few examples of the abundance of some valuable metals in the Earth’s crust:

Aluminum: 8.1%
Copper: 0.0068%
Gold: 0.000004 ppm (parts per million)
Iron: 5.6%
Lead: 0.0013%
Platinum: 0.000005 ppm
Silver: 0.000075%
Uranium: 0.00015%
Zinc: 0.0075%

It’s important to note that these figures represent the average abundance of these metals across the entire Earth’s crust, and the actual concentrations can vary widely in different regions and deposits.

Consider Canada, one of the world’s largest manufacturers. Canada has the largest mining regions in the world and has been one of the biggest suppliers for the last 150 years.
Canada earns a lot of income in Canada’s mining industry. Most of these are significant amounts of gold, iron, copper and potash, which are less important than nickel and diamond, but with less amounts. Revenues from the oil sector are higher than $ 100 billion annually.

The value of various Canadian mining sectors in 2013 [SE from data at http://www.nrcan.gc.ca/mining-materials/publications/8772]

A metal deposition is a rock mass in which one or more metals are concentrated to the point where it is economically suitable for recovery. Some background levels of important metals in average rocks are shown in the Table with typical grades required to form a suitable residue and their corresponding concentration factors. For example, when we look at the copper, we see that although the average rock is about 40 ppm (parts per million) of copper, about 10,000 ppm or 1% is required to obtain a suitable copper residue. In other words, copper ore contains 250 times as much copper as the typical rocks. The concentration factors for other elements in the list are much higher. 2,000 for gold and 10,000 for silver.

Typical background and ore levels of some important metals

Metal	Typical Background Level	Typical Economic Grade*	Concentration Factor
Copper	40 ppm	10,000 ppm (1%)	250 times
Gold	0.003 ppm	6 ppm (0.006%)	2,000 times
Lead	10 ppm	50,000 ppm (5%	5,000 times
Molybdenum	1 ppm	1,000 ppm (0.1%)	1,000 times
Nickel	25 ppm	20,000 ppm (2%)	800 times
Silver	0.1 ppm	1,000 ppm (0.1%)	10,000 times
Uranium	2 ppm	10,000 ppm (1%)	5,000 times
Zinc	50 ppm	50,000 ppm (5%)	1,000 times

It is clear that some very important concentrations need to occur in order to create a precious residue. This concentration may occur during the formation of the host rock or after rock formation by several different types of processes. There are a wide variety of ore forming processes and hundreds of mineral deposits

Magmatic deposits

Magmatic deposits are mineral deposits that are associated with igneous rocks, such as granite, gabbro, and basalt. They are formed by the cooling and crystallization of magma or lava, which can result in the concentration of various minerals within the solidified rock. Magmatic deposits can be further subdivided into two main types: intrusive and extrusive.

Intrusive magmatic deposits, also known as plutonic deposits, are formed when magma solidifies within the Earth’s crust. As the magma cools, minerals begin to crystallize out of the melt and become concentrated in certain parts of the rock. The resulting deposits can be massive in size and can contain high concentrations of valuable minerals, such as copper, nickel, platinum, and gold.

Extrusive magmatic deposits, also known as volcanic deposits, are formed when magma or lava erupts onto the Earth’s surface and solidifies. These deposits can be found in the form of lava flows, volcanic ash, and other volcanic rocks. Some examples of extrusive magmatic deposits include massive sulfide deposits, which are rich in copper, zinc, and lead, and platinum-group element deposits, which are rich in platinum, palladium, and rhodium.

Magmatic deposits can be economically important sources of various metals and minerals, and they are often the targets of mining and exploration activities.

Contents

Types of magmatic deposits
Porphyry Deposits
Skarn Deposits
Pegmatite Deposits
Kimberlite Deposits
Carbonatite Deposits
Formation processes and mineralogy
Examples of notable magmatic deposits

Types of magmatic deposits

Magmatic deposits are formed from magma, which is molten rock that originates from the Earth’s mantle or lower crust. As the magma cools and solidifies, it can concentrate certain elements, which can form deposits of valuable minerals.

There are several types of magmatic deposits, including:

Porphyry Deposits: These are the most common type of magmatic deposit and are typically found in copper and gold mining operations. Porphyry deposits form when magma intrudes into the earth’s crust, and minerals are deposited as the magma cools and solidifies. Porphyry deposits are generally low-grade but large-tonnage operations that require significant amounts of processing.
Skarn Deposits: Skarn deposits are formed by the interaction of magma with carbonate rocks. The heat and fluids from the magma alter the carbonate rocks, creating a zone of mineralization called a skarn. Skarn deposits are known for their high-grade deposits of copper, gold, silver, and tungsten.
Pegmatite Deposits: These deposits are known for their coarse-grained nature, which makes them easier to mine. Pegmatites are formed from the late-stage cooling of magma and contain a variety of minerals, including rare earth elements, lithium, and tantalum. Pegmatite deposits are usually small, but the high concentration of valuable minerals can make them economically viable.
Kimberlite Deposits: Kimberlite deposits are formed from the eruption of deep-source magma and are known for their diamond-bearing nature. The volcanic eruptions bring the diamonds to the surface, where they can be mined. However, the diamond deposits within kimberlite are generally small and sporadic, making mining operations difficult and costly.
Carbonatite Deposits: These deposits are formed by the cooling and solidification of carbonatite magma. Carbonatite deposits are known for their rare earth element deposits and are typically mined for these elements, which are used in high-tech applications.

Each of these magmatic deposits has its own unique characteristics, and their economic viability depends on a variety of factors, including the grade and tonnage of the deposit, the accessibility of the deposit, and the market demand for the minerals contained within the deposit.

Porphyry Deposits

Porphyry deposits are a type of magmatic deposit that are economically important sources of copper, molybdenum, and gold, as well as other metals. They are named after the texture of the rocks that host the mineralization, which consists of large crystals, or phenocrysts, embedded in a finer-grained matrix, or groundmass.

Porphyry deposits are formed by the intrusion of magmas into the Earth’s crust, which can create large, deep-seated magma chambers. As these chambers cool and solidify, hydrothermal fluids are released, which can carry metals and other elements. These fluids migrate through fractures and other permeable structures in the surrounding rock, and can precipitate mineralization as they cool and interact with the host rocks.

Porphyry deposits are typically large and low-grade, with mineralization occurring over broad areas. They can also be polymetallic, meaning that they contain multiple metals of economic interest. Some of the world’s largest copper and gold mines are porphyry deposits, including the Bingham Canyon mine in Utah, USA, and the Grasberg mine in Indonesia.

Skarn Deposits

Skarn deposits are formed when hydrothermal fluids interact with carbonate-rich rocks, such as limestone or marble, resulting in the replacement of the original minerals by a variety of minerals, including those of economic interest. Skarns can host a wide range of metallic minerals, including copper, gold, silver, lead, zinc, tungsten, and molybdenum.

The formation of skarn deposits typically involves the following process:

Intrusion of igneous rocks, which provide a heat and fluid source.
Interaction of the igneous rocks with carbonate-rich sedimentary rocks, leading to the replacement of the carbonate minerals with new minerals.
Deposition of economic minerals within the skarn.

Skarn deposits are often associated with porphyry deposits, as both are typically formed by the same hydrothermal system. Examples of skarn deposits include the Antamina deposit in Peru and the Mt. Skukum deposit in Canada.

Pegmatite Deposits

Pegmatite deposits are a type of magmatic deposit that are composed of unusually large crystals or masses of minerals that are commonly formed in the final stages of the crystallization of a magma. Pegmatites are generally coarse-grained and often contain rare or unusual minerals, making them of interest to mineral collectors and occasionally of economic interest. Some of the minerals commonly found in pegmatites include feldspar, mica, quartz, tourmaline, topaz, and beryl.

Pegmatites are typically found in association with granite, and they are commonly emplaced along the margins of granite plutons or within the plutons themselves. They can also occur as dikes or veins that cut across other rocks. The formation of pegmatites is thought to be related to the slow cooling of the magma and the consequent growth of large crystals, as well as to the presence of water and other volatile elements in the magma. Because of their unusual mineralogy and large crystal size, pegmatites can sometimes be important sources of industrial minerals, gemstones, and rare metals.

Kimberlite Deposits

Kimberlite is a type of rock that is known for containing diamonds. Kimberlite is named after the town of Kimberley in South Africa, where the first diamonds found in kimberlite were discovered. Kimberlite is a type of volcanic rock that is formed from magma that rises from the Earth’s mantle and cools relatively quickly, preserving many of the mantle’s characteristics. Kimberlite pipes are the most important source of diamonds in the world. The diamonds in kimberlite pipes are thought to have originated deep in the Earth’s mantle and were brought to the surface by volcanic activity. Other minerals found in kimberlite include olivine, pyroxene, and garnet.

Carbonatite Deposits

arbonatite deposits are another type of magmatic deposit that are relatively rare but can be economically important. These deposits are characterized by their high concentrations of rare earth elements (REE), which are used in a variety of high-tech applications, such as electronics, magnets, and batteries.

Carbonatites are igneous rocks that are composed primarily of carbonate minerals, such as calcite and dolomite, as well as other minerals, such as apatite, magnetite, and phlogopite. They are believed to form from carbonatitic magma that originates deep within the mantle and rises to the surface, either directly or through the process of assimilation, where it cools and solidifies.

The Bayan Obo deposit in China is one of the largest carbonatite deposits in the world and is a major source of REEs. Other notable carbonatite deposits include the Palabora complex in South Africa, the Mount Weld deposit in Australia, and the Mountain Pass deposit in the United States.

Formation processes and mineralogy

Magmatic deposits form from the cooling and crystallization of magma, which can lead to the concentration of certain minerals into economic deposits. The mineralogy of magmatic deposits depends on the composition of the original magma and the conditions under which it cooled and crystallized.

The minerals commonly associated with magmatic deposits include sulfides, oxides, and silicates of metals such as copper, nickel, platinum, palladium, gold, and silver. These metals tend to be more concentrated in the denser and heavier minerals, which sink to the bottom of the magma chamber during the cooling and solidification process.

The mineralogy of magmatic deposits can also be influenced by the presence of volatile elements such as sulfur, chlorine, and fluorine, which can cause the formation of minerals such as apatite, magnetite, and fluorite. In addition, the cooling and solidification of magma can lead to the formation of minerals such as feldspar, mica, and quartz, which can sometimes be economically valuable.

Examples of notable magmatic deposits

There are many notable magmatic deposits around the world. Here are a few examples:

Norilsk-Talnakh, Russia: This deposit is one of the largest sources of nickel and palladium in the world. It is located in the Siberian Traps, which are part of a large igneous province that was formed during the Permian-Triassic extinction event.
Bushveld Complex, South Africa: This layered mafic intrusion is one of the world’s largest sources of platinum and chromium. The deposit is about 2 billion years old and covers an area of about 66,000 square kilometers.
Sudbury Basin, Canada: This basin is one of the largest impact structures on Earth and contains a massive magmatic deposit that is rich in nickel, copper, and platinum group metals. The deposit was formed by a meteorite impact about 1.8 billion years ago.
Palabora, South Africa: This deposit is one of the world’s largest sources of copper and contains significant amounts of gold and silver. It is located in a large carbonatite complex that was formed about 2 billion years ago.
Stillwater Complex, USA: This layered mafic intrusion in Montana is a major source of platinum group metals and contains significant amounts of chromium and copper. The deposit is about 2.7 billion years old and covers an area of about 2,600 square kilometers.

These deposits are just a few examples of the many magmatic deposits that have been discovered around the world.

Manganite

Manganite is a member of oxide minerals with composed of manganese oxide-hydroxide of formula: MnO(OH).A widespread and important ore of manganese. The mineral had been described by a number of different names since 1772, but was finally given its current name, which it owes to its manganese component, in 1827. Opaque and metallic dark gray or black, crystals of manganite are mostly pseudoorthorhombic prisms, typically with flat or blunt terminations, and are often grouped in bundles and striated lengthwise. Multiple twinning is common. Manganite can also be massive or granular; it is then hard to distinguish by eye from other manganese oxides, such as pyrolusite. An important ore of manganese, manganite occurs in hydrothermal deposits formed at low temperature (up to 400°F/200°C) with calcite, siderite, and barite, and in replacement deposits with goethite. Manganite also occurs in hot-spring manganese deposits. It alters to pyrolusite and may form by the alteration of other manganese minerals.

The mineral contains 89.7% manganese sesquioxide; it dissolves in hydrochloric acid with evolution of chlorine.

Name: For MANGANese in the composition.

Association: Pyrolusite, braunite, hausmannite, barite, calcite, siderite, goethite.

Polymorphism & Series: Trimorphous with feitknechtite and groutite

Environment: In low temperature hydrothermal replacement deposits, acid-rich bogs, and in manganese-rich hot springs.

Composition: MnO(OH). Mn = 62.4 per cent, 0 = 27.3 percent, H20 = 10.3 percent.

Diagnostic Features: Told chiefly by its black color, prismatic crystals, hardness (4), and brown streak. The last two will serve to distinguish it from pyrolusite.

Crystallography: Orthorhombic; dipyramidal. Crystals usually long prismatic with obtuse terminations, deeply striated vertically. Often twinned. Crystals often grouped in bundles or in radiating masses; also columnar.

Contents

Chemical Properties
Manganite Physical Properties
Manganite Optical Properties
Occurrence
Manganite Uses Area
Distribution
Reference

Chemical Properties

Chemical Classification	Oxide mineral
Formula	MnO(OH)
Common Impurities	Fe,Ba,Pb,Cu,Al,Ca

Manganite Physical Properties

Crystal habit	Slender prismatic crystals, massive to fibrous, pseudo-orthorhombic
Color	Gray-black, black
Streak	Reddish brown to black
Luster	Resinous, Sub-Metallic, Dull
Cleavage	Perfect {010} perfect; {110} and {001} good.
Diaphaneity	Opaque
Mohs Hardness	4
Crystal System	Monoclinic
Tenacity	Brittle
Density	4.29 – 4.34 g/cm3 (Measured) 4.38 g/cm3 (Calculated)
Fracture	Splintery

Manganite Optical Properties

Type	Anisotropic
Anisotropism	Weak
Color / Pleochroism	Weak
2V:	Small
RI values:	nα = 2.250(2) nβ = 2.250(2) nγ = 2.530(2)
Twinning	Contact and penetration Twins on {011}; lamellar on {100}.
Optic Sign	Biaxial (+)
Birefringence	0.028
Relief	Very High
Dispersion:	r > v extreme

Occurrence

Formed in low-temperature hydrothermal or hot-spring manganese deposits; replacing other manganese minerals in sedimentary deposits; a component in some clay deposits and laterites.

Manganite is found associated with other manganese oxides and has a similar origin. It frequently alters to pyrolusite. Found often in veins associated with the granitic igneous rocks, both filling cavities and as a replacement of the neighboring rocks. Barite and calcitc are frequent associates.

Manganite Uses Area

A minor ore of manganese.
In mineral prehistoric times, a pigment has been used by humans and as the igniter of Neanderthals. Manganite is believed to be used in prehistoric times to burn wood fire. Manganite reduces the combustion temperature of the wood from 350 degrees Celsius to 250 degrees Celsius. Manganite dust is a common finding in Neanderthal archaeological sites.

Distribution

Many localities, but rarely well-crystallized.

Fine crystals from Ilfeld, Harz Mountains, and Ilmenau, Thuringia, Germany.
In the Botallack mine, St. Just, Cornwall; from Egremont, Cumbria; and at Upton Pyne, Exeter, Devonshire, England.
From Granam, near Towie, Aberdeenshire, Scotland.
At Bolet, near Karlsborg, Vastergotland,Sweden.
In the USA, good crystals from the Negaunee and Marquette districts, Marquette Co., Michigan; in the Powell’s Fort mine, near Woodstock, Shenandoah Co., Virginia; and at Lake Valley, Sierra Co., New Mexico.
From the Caland mine, Atikokan, Ontario, Canada.
At Kuruman, Cape Province, South Africa.

Reference

Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
Dana, J. D. (1864). Manual of Mineralogy… Wiley.
Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].

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