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.
Magmatic deposits
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.
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 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
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
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 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
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, Northern Cape Province, South AfricaManganite, Thuringia, GermanyManganite, Northern Cape Province, South Africa
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.
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.
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].
Turquoise-pyrite-quartzTurquoise, Bishop Mine, River Manganese District, Campbell County, Virginia, USATurquoise pebble, made by tumbling the rough rock in a rotating drum with abrasive.
Turquoise is a
member of phosphate mineral with chemical the formula CuAl6 (PO4)4(OH) 8·4H2O.
Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of
copper and aluminium. Beads made of turquoise that date back to c.5000 BCE have
been recovered in Mesopotamia (present-day Iraq). This mineral usually occurs
in massive or microcrystalline forms, as encrustations or nodules, or in veins.
Crystals are rare; when found, they occur as short, often transparent prisms.
Turquoise varies in color from sky-blue to green, depending on the amount of
iron and copper it contains. Turquoise occurs in arid environments as a
secondary mineral probably derived from the decomposition of apatite and some
copper sulfides. One of the first gemstones to be mined. It is uncommon and
precious in the finer grades and has been offered as gemstone and ornamental
stones for hundreds of years because of its unique tone. Recently, turquoise,
like many other opaque jewels, has been devalued with access into the market of
treatments, imitations and synthetics.
As a secondary mineral, turquoise is formed through the leaching impact of acidic aqueous answers for the duration of the decomposition and oxidation of pre-existing minerals. As an example, copper can also come from number one copper sulphides such as chalcopyrite or from secondary carbonates of malachite or azurite; derived from aluminumfeldspar; and phosphorus from apatite. Because turquoise is regularly discovered in arid areas, generally in crammed or volcanic rocks, often in turquoise regions that fill or absorb cavities and cracks filled with related limonite and different iron oxides, weather factors play an critical role. Inside the southwestern u.s.a., turquoise is sort of continually unchanged with the decomposition merchandise of copper sulphide deposits in or round potassium-feldspar-containing porphyritic interventions. In some formations, alunite, potassium aluminum sulfate, is a distinguished secondary mineral. Typically turquoise mineralization is constrained to a shallow intensity of much less than 20 meters (66 ft), but happens at deeper fracture zones wherein the secondary solutions have greater penetration or the intensity of the water desk is greater.
Chemical Properties
Chemical Classification
Phosphate minerals
Formula
CuAl6(PO4)4(OH)8·4H2O
Common Impurities
Fe,Ca
Name: Turquois is
French and means Turkish, the original stones having come into Europe from the Iranian
locality through Turkey.
Polymorphism &
Series: Forms two series, with chalcosiderite, and with planerite.
Mineral Group: Turquoise
group
Crystallography:
Triclinic; pinacoidal. Rarely in minute crystals, usually cryptocrystalline.
Massive compact, reniform,- stalactitic. In thin seams, incrustations and
disseminated grains.
TurquoiseComposition: A basic hydrous phosphate
of aluminum, Al2 (0H)3P04- H20. Excluding CuO reported in chemical analyses of
turquois, the percentages of the oxides are: A120 3 = 46.8, P2Or, = 32.6, H20 =
20.6. The mineral is colored by small amounts of copper whose role in the
composition is not well understood.
Diagnostic Features: Turquois
can be easily recognized by its color. It is harder than ehrysocolla, the only
common mineral which it resembles.
TurquoiseUses: As a gem stone. It is always cut
in round or oval forms. Much turquois is cut which is veined with the various
gangue materials, and such stones are sold under the name of turquois matrix.
Turquoise Physical Properties
Crystal habit
Massive,
nodular
Color
Bright
blue, sky-blue, pale green, blue-green, turquoise-blue, apple-green,
green-gray
Turquoise become most of the first mined stones, and even
though a number of them are still studied today, many historical web sites are
extinct. Those are all small-scale operations; because of the limited scope and
distance of deposits, they’re generally seasonal. Most manually perform with
very little mechanization. However, turquoise is often recycled as a of
massive-scale copper mining operations, particularly within the United States
of America.
Iran: Iran has
been vital turquoise source for at least 2,000 years. It was to begin with
called “pērōzah” by the Iranians, meaning “victory”, after
which the Arabs were known as “fayrūzah”, which changed into
mentioned “fīrūzeh” in contemporary Persian. In Iranian structure,
blue turned into used to cover the domes of turquoise palaces, due to the fact
the intense blue colour changed into additionally a symbol of heaven on earth.
Sinai: as a
minimum the primary Dynasty (BCE 3000) in historical Egypt, and probably earlier
than it, turned into utilized by the turquoise Egyptians and became extracted
by means of them in the Sinai Peninsula. This vicinity turned into regarded by
the local Monitu as the Turquoise use. There are six mines at the southwest
coast of the peninsula, overlaying an area of approximately 650 rectangular
kilometers (250 square meters). The maximum vital of these mines are Serabit
al-Khadim and Wadi Maghareh, traditionally believed to be one of the oldest
known mines. The historic mine is ready four kilometers from an historical
temple devoted to the gods Hathor.
USA: The
Southwest United States is a crucial turquoise supply; Arizona, California (San
Bernardino, Imperial, Inyo counties), Colorado (Conejos, El Paso, Lake,
Saguache counties), New Mexico (Eddy, grant, Otero, Santa Fe counties) and
Nevada (Clark, Elko, Esmeralda County, Eureka) Lander, Mineral County and Nye
counties). California and New Mexico’s deposits had been extracted by way of
native individuals, pre-Columbian, using stone equipment, a few nearby and a
few as far flung as valuable Mexico. Cerrillos is notion to be the website of
the oldest mines in New Mexico; before the Nineteen Twenties the country was
the USA’s largest producer; extra or much less exhausted today. A mine
positioned within the Apache Canyon in California is currently in industrial
ability.
Different Sources:
Turquoise prehistoric artifacts (beads) had been regarded from BCE’s regions
inside the Japanese Rhodopes in Bulgaria for the fifth millennium – the supply
of uncooked materials is probably associated with the close by Spahievo
lead-zinc ore field.
China has been a small turquoise supply for extra than 3000
years. The jewel-great fabric inside the shape of compact nodules is observed
inside the damaged, silicified limestones of Yunxian and Zhushan in Hubei
province. Further, Marco Polo pronounced the presence of turquoise in
contemporary Sichuan. Maximum Chinese materials are exported, but there are
numerous carvings carved like jade. In Tibet, the Derge and Nagari-Khorsum
mountains in the east and west of the place are claimed to have
jewel-first-rate deposits.
Different noteworthy places are: Afghanistan; Australia
(Victoria and Queensland); North India; Northern Chile (Chuquicamata);
Cornwall; Saxony; Silesia; and Turkestan.
Turquoise Optical Properties
Color / Pleochroism
Weak
X= colorless
Z= pale blue or pale green
2V:
Measured: 40° , Calculated: 44°
RI
values:
nα = 1.610 nβ = 1.615 nγ = 1.650
Optic Sign
Biaxial (+)
Birefringence
0.040
Relief
Moderate
Dispersion:
r < v strong
Distribution
Dozens of localities, of which only a few can be mentioned,
for commercial amounts or good crystals.
In Iran, at Madan, 45 km northwest of Neyshabur
(Nishapur).
From Ottre, near Vielsalm, Belgium.
At the Bunny mine, St. Austell, and elsewhere in
Cornwall, England.
From Katonto, north of Kolwezi, Katanga
Province, Congo (Shaba Province, Zaire), good crystals.
In the USA, crystallized from the Bishop mine,
Lynch Station, Campbell Co., Virginia; in the Cerrillos district, Santa Fe Co.,
and the Burro Mountains district, Grant Co., New Mexico; in Arizona, commercial
production from Mineral Park, Mohave Co., Morenci, Greenlee Co., the
Globe-Miami district, Gila Co., and others; numerous small deposits in Lander
Co. and elsewhere in Nevada.
In the Itatiaiucu iron mine, southwest of Belo
Horizonte, Minas Gerais, Brazil, large crystals.
At Chuquicamata, Antofagasta, Chile.
In Australia, at Narooma, New South Wales, as
crystals; in the Iron Monarch quarry, Iron Knob, South Australia.
In China, from Yunxian and Zhushan, Wudang
Mountains, Hubei Province, and near Shanyang, Shaanxi Province.
References
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].
Wikipedia contributors. (2019, June 25). Turquoise. In Wikipedia, The Free Encyclopedia. Retrieved 02:25, July 9, 2019, from https://en.wikipedia.org/w/index.php?title=Turquoise&oldid=903470553
Chrysoberyl is a mineral and gemstone that belongs to the beryl family. It is known for its unique optical properties, durability, and various color varieties. The name “chrysoberyl” is derived from the Greek words “chrysos” meaning gold and “beryllos” meaning beryl, which reflects the golden to greenish hues that are commonly associated with this mineral.
Chrysoberylchrysoberyl var. alexandritechrysoberyl var. alexandrite under UV light long waves
Chrysoberyl is a beryllium aluminum oxide mineral with the chemical formula BeAl2O4. It forms in the orthorhombic crystal system and is typically found as prismatic crystals. Chrysoberyl is most renowned for its exceptional hardness (8.5 on the Mohs scale) and its pleochroism, which is the ability to display different colors when viewed from different angles.
Chemical Composition and Crystal Structure:
The chemical composition of chrysoberyl consists of beryllium, aluminum, and oxygen. It is composed of a three-dimensional framework of aluminum and beryllium ions bonded to oxygen atoms. The specific arrangement of these atoms gives rise to the crystal structure of chrysoberyl.
Chrysoberyl crystals are usually elongated and can be found in various colors, including yellow, green, brown, and even colorless. The greenish-yellow to yellowish-green variety is the most well-known and is often referred to simply as “chrysoberyl.” Another notable variety is “alexandrite,” which exhibits a unique color-changing property, appearing green in daylight and red under incandescent light.
Historical Significance and Uses:
Chrysoberyl has a long history of use as a gemstone and has been valued for centuries. The most famous variety, alexandrite, was first discovered in the Ural Mountains of Russia in the 1830s and was named after the Russian tsar, Alexander II. Alexandrite’s remarkable color-changing ability made it particularly cherished among collectors and jewelry enthusiasts.
Chrysoberyl’s hardness and durability make it suitable for various jewelry applications, especially for items like rings and earrings that are exposed to daily wear. While alexandrite is a rare and sought-after collector’s gem, other chrysoberyl varieties, such as the cat’s-eye chrysoberyl, are also popular due to their unique optical phenomena.
In addition to its use in jewelry, chrysoberyl has been used in some scientific and industrial applications due to its resistance to heat, chemicals, and abrasion. However, its primary appeal lies in its use as a gemstone prized for its beauty, durability, and exceptional optical properties.
Chrysoberyl is a mineral that comes in various types and varieties, each with its own unique characteristics and colors. Here are some of the most notable types and varieties of chrysoberyl:
Chrysoberyl: This is the general term used to refer to the yellow, yellow-green, or greenish-yellow variety of the mineral. It is often valued for its brilliance and durability, making it a popular choice for gemstone jewelry. While it lacks the color-changing property of alexandrite, it still possesses the pleochroic effect that can give it different colors when viewed from different angles.
Alexandrite: Alexandrite is one of the most famous and valuable varieties of chrysoberyl due to its unique color-changing property. It appears green in natural daylight and shifts to a reddish or purplish hue under incandescent light. This dramatic color change is a result of the presence of chromium in its crystal structure. Alexandrite is highly sought after by collectors and gem enthusiasts for its rarity and mesmerizing optical characteristics.
Cat’s-Eye Chrysoberyl: This variety of chrysoberyl exhibits a captivating phenomenon known as chatoyancy or the “cat’s-eye effect.” When cut as a cabochon, it displays a bright, narrow band of light that appears to glide across the surface of the gemstone when it’s moved. This effect is caused by needle-like inclusions of fibers or tubes within the crystal structure that reflect light in a concentrated line. The cat’s-eye effect can be seen in various colors of chrysoberyl, including yellow, green, and brown.
Cymophane: Cymophane is another name for cat’s-eye chrysoberyl due to its distinctive chatoyant effect. The term “cymophane” comes from the Greek words “kyma,” meaning wave, and “phanos,” meaning appearance, referring to the wavy appearance of the cat’s-eye effect.
Yellow Chrysoberyl: This variety of chrysoberyl is valued for its pure yellow color. It lacks the strong green hues found in some other varieties and is often cut into faceted gemstones for use in jewelry.
Green Chrysoberyl: This variety leans more toward green hues than the yellow varieties. It can vary in shades from pale green to a more intense, vibrant green. Green chrysoberyl is often used in jewelry as well, and its durability makes it suitable for various types of jewelry settings.
Brown Chrysoberyl: Brown chrysoberyl is less common and tends to be less valued for gemstone use compared to other color varieties. It can still display the pleochroic effect but is less popular due to its less attractive color.
Colorless Chrysoberyl: While colorless chrysoberyl lacks the vibrant hues of other varieties, its brilliance and hardness still make it a valuable gemstone for certain jewelry designs. It is relatively rare and can be used as an alternative to diamond in some instances.
These are some of the main types and varieties of chrysoberyl, each with its own distinctive features and appeal. Whether valued for their color-changing properties, chatoyancy, or vivid colors, chrysoberyl gemstones have captured the fascination of gem enthusiasts and collectors around the world.
Physical Properties of Chrysoberyl
Chrysoberyl is a mineral with several distinctive physical properties:
Color: Chrysoberyl occurs in a range of colors, including yellow, green, brown, and colorless. The most well-known color variety is the yellow to greenish-yellow, often referred to as simply “chrysoberyl.” The color can vary based on trace elements present in the crystal structure.
Crystal Structure: Chrysoberyl crystallizes in the orthorhombic crystal system. It typically forms prismatic crystals that can be elongated. The crystal structure is what gives rise to its unique optical properties.
Hardness: Chrysoberyl is one of the hardest gemstones, with a hardness of 8.5 on the Mohs scale. This makes it highly resistant to scratching and abrasion, making it suitable for everyday jewelry wear.
Cleavage: Chrysoberyl has poor to indistinct cleavage, meaning it doesn’t break along well-defined planes like some other minerals. Instead, it tends to fracture conchoidally, producing smooth, curved surfaces when broken.
Specific Gravity: The specific gravity of chrysoberyl typically ranges from 3.5 to 3.8, indicating its relatively high density.
Color Variations and Phenomena:
Chrysoberyl exhibits various color variations and optical phenomena that contribute to its allure:
Color Change: The most famous color-changing variety of chrysoberyl is alexandrite. This gemstone displays a remarkable color change from green or bluish-green in daylight to purplish-red or reddish-purple under incandescent light. This phenomenon is caused by the presence of chromium and its interaction with light.
Pleochroism: Chrysoberyl is pleochroic, which means it can display different colors when viewed from different angles. This is particularly noticeable in the green to yellow varieties, where the gem may appear green when viewed from one angle and yellow from another.
Hardness and Durability:
Chrysoberyl’s exceptional hardness and durability make it highly resistant to wear and damage:
Hardness: With a hardness of 8.5 on the Mohs scale, chrysoberyl is surpassed in hardness only by a few gemstones like diamond, corundum (sapphire and ruby), and moissanite. Its hardness ensures that it can withstand daily wear without easily acquiring scratches.
Durability: Chrysoberyl’s hardness also contributes to its overall durability. It is resistant to scratching, chipping, and abrasion, making it suitable for a wide range of jewelry applications.
Optical Characteristics and Luster:
Chrysoberyl’s optical properties enhance its visual appeal and contribute to its desirability:
Luster: Chrysoberyl has a vitreous to adamantine luster, giving it a bright and reflective appearance when well-polished.
Chatoyancy (Cat’s-Eye Effect): In cat’s-eye chrysoberyl, a phenomenon known as chatoyancy occurs. When cut as a cabochon, a distinct band of light, resembling a cat’s-eye, appears to glide across the surface of the gemstone when it’s moved. This effect is caused by the presence of fibrous or tubular inclusions that reflect light in a concentrated line.
Color Saturation: The color saturation of chrysoberyl can vary, affecting its visual impact. Intensely colored varieties, such as the vibrant green or golden-yellow ones, are particularly prized.
In summary, chrysoberyl’s physical properties, including its color variations, unique optical phenomena, exceptional hardness, and luster, contribute to its appeal as a valued and versatile gemstone for jewelry and collectors alike.
Geological Occurrence
Chrysoberyl (beryllium aluminium oxide) from the Ural Mountains in the Perm province of Russia. Cotton Collection, Keele.
Chrysoberyl is primarily formed in pegmatite veins, which are coarse-grained igneous rocks found in various geological settings. It often occurs in association with other minerals and gemstones, such as beryl (including emerald and aquamarine), mica, feldspar, and quartz. Chrysoberyl can also be found in metamorphic rocks, particularly those that have undergone high-pressure and high-temperature conditions.
Formation Processes:
The formation of chrysoberyl involves geological processes that occur deep within the Earth’s crust:
Pegmatite Formation: Chrysoberyl commonly forms in pegmatite veins, which are formed during the late stages of crystallization of molten rock (magma). Pegmatites are known for producing larger crystals due to their slow cooling and the availability of various elements during the crystallization process.
Metamorphism: Chrysoberyl can also form through metamorphic processes. When pre-existing minerals are subjected to high pressure and temperature conditions within the Earth’s crust, they can transform into new minerals. Chrysoberyl may form as a result of such transformations under specific metamorphic conditions.
Chrysoberyl can be found in various locations around the world. Some notable deposits include:
Brazil: Brazil is one of the most significant sources of chrysoberyl. It produces both the yellow and green varieties, including cat’s-eye chrysoberyl. Minas Gerais, a Brazilian state, is particularly famous for producing high-quality chrysoberyl.
Sri Lanka: Sri Lanka is known for its production of chrysoberyl, including cat’s-eye chrysoberyl. The gemstone deposits in Sri Lanka have been known for centuries and have contributed to the global supply of chrysoberyl.
Russia: Russia, specifically the Ural Mountains, is historically significant for the discovery of alexandrite in the early 19th century. Alexandrite’s unique color-changing property has made it highly sought after among collectors.
Madagascar: Madagascar is another source of chrysoberyl, including both cat’s-eye and non-cat’s-eye varieties. The island nation has produced a range of chrysoberyl colors, adding to the gemstone’s global availability.
India: Chrysoberyl can also be found in various regions of India. While not as well-known as some other sources, India has contributed to the overall supply of chrysoberyl.
Other Locations: Chrysoberyl can also be found in smaller quantities in other countries, including Myanmar (Burma), Zimbabwe, Tanzania, and the United States.
It’s important to note that the quality and quantity of chrysoberyl deposits can vary from location to location. Additionally, the specific color varieties and optical phenomena found in chrysoberyl can make certain deposits more valuable or sought after by collectors and gem enthusiasts.
Alexandrite: The Color-Changing Gem
Alexandrite is a remarkable and highly prized variety of chrysoberyl due to its exceptional color-changing property. This unique gemstone is known for its ability to exhibit different colors under varying lighting conditions, making it a true marvel of the mineral world.
Color-Changing Phenomenon:
The most distinctive feature of alexandrite is its ability to change color depending on the light source. This phenomenon, known as the “alexandrite effect,” is a result of the gem’s interaction with different wavelengths of light. Alexandrite appears green in daylight or natural light and shifts to a reddish or purplish hue under incandescent or artificial light.
This color change is a result of the presence of trace amounts of chromium in the crystal structure of alexandrite. Chromium absorbs certain wavelengths of light and emits others, causing the gemstone to display different colors depending on the light source’s composition. The precise combination of chromium content, the crystal lattice, and the lighting conditions contribute to the gem’s unique dual-color appearance.
chrysoberyl var. alexandrite under UV light long waves
Discovery and Naming:
Alexandrite was first discovered in the Ural Mountains of Russia in the early 1830s. It was named after Alexander II, the future Russian tsar, to honor his coming of age. The green and red colors of alexandrite also happened to be the primary colors of the Russian imperial army. This naming was a fitting tribute to the young heir to the throne.
Desirable Color Combinations:
The most valued alexandrite specimens exhibit the most dramatic and pronounced color change—changing from a vibrant green or bluish-green in daylight to a vivid red or purplish-red under incandescent light. The more distinct the contrast between the colors and the more intense the hues, the more valuable the alexandrite is considered.
Rarity and Collectibility:
Alexandrite is incredibly rare, and high-quality specimens are among the most valuable gemstones in the world. Factors contributing to its rarity include the specific conditions required for the presence of chromium, the necessary geological processes, and the unique optical properties that make true alexandrite so uncommon.
Due to its scarcity and mesmerizing color-changing ability, alexandrite has captured the attention of gem collectors, jewelry enthusiasts, and connoisseurs for centuries. The gemstone’s scarcity, combined with its captivating optical properties, has led to its status as one of the most sought-after and treasured gems in the world.
In summary, alexandrite stands out as a stunning example of nature’s artistry, showcasing the fascinating color-changing phenomenon caused by the presence of chromium. Its rarity, captivating appearance, and historical significance make it a prized gemstone that continues to captivate those who have the opportunity to admire its remarkable colors.
Cat’s Eye Chrysoberyl: The Phenomenal Gem
Cat’s Eye Chrysoberyl is a captivating and highly sought-after variety of chrysoberyl known for its mesmerizing optical phenomenon called chatoyancy, which creates the appearance of a distinct band of light resembling a cat’s eye moving across the surface of the gemstone. This unique effect makes Cat’s Eye Chrysoberyl a remarkable and cherished gemstone among collectors and jewelry enthusiasts.
Chatoyancy (Cat’s-Eye Effect):
The cat’s-eye effect displayed by Cat’s Eye Chrysoberyl is a result of a specific type of inclusion within the gemstone. Inclusions are minute features trapped within the crystal structure during its formation. In the case of cat’s-eye chrysoberyl, these inclusions are often composed of fine, parallel-oriented fibers or tubes known as “silk.” The inclusions are distributed in such a way that they intersect the surface of the gemstone perpendicular to its length.
When light enters the gemstone and interacts with these fine inclusions, it is reflected along the length of the fibers or tubes. This concentrated reflection creates a luminous band of light that appears as a single bright line across the surface of the gem, reminiscent of the slit-shaped pupil of a cat’s eye. As the gem is moved or rotated, this band of light appears to move as well, creating the illusion of a “cat’s eye” opening and closing.
Formation of Chatoyant Effect:
The chatoyant effect in Cat’s Eye Chrysoberyl is a result of the gem’s growth process. During the gem’s formation within pegmatite veins or metamorphic environments, mineral-rich fluids containing beryllium, aluminum, and other elements slowly crystallize, allowing fine inclusions like silk to become aligned in parallel patterns. These aligned inclusions are what give rise to the unique cat’s-eye effect.
Variety of Colors:
Cat’s Eye Chrysoberyl can exhibit a range of colors, including golden-yellow, green, brown, and gray. The most valued colors are typically the more intense shades of green and golden-yellow. The cat’s-eye effect is especially pronounced in well-cut cabochon gemstones, where the light is concentrated along the length of the silk inclusions.
Value and Rarity:
Cat’s Eye Chrysoberyl is highly valued due to its rarity and the mesmerizing chatoyant effect. The quality of the chatoyancy, the intensity of the color, the sharpness of the cat’s-eye band, and the overall clarity of the gemstone all influence its value. Premium cat’s-eye chrysoberyl gemstones with well-defined, bright, and centered bands of light are considered exceptionally valuable and can command high prices in the market.
Symbolism and Use:
Cat’s Eye Chrysoberyl has been associated with protective and mystical qualities in various cultures. It is believed to bring luck, enhance intuition, and protect its wearer from negative energies. Due to its unique appearance and symbolism, cat’s-eye chrysoberyl is often used in fine jewelry designs, including rings, pendants, and earrings, where its captivating chatoyancy can be prominently displayed and admired.
In conclusion, Cat’s Eye Chrysoberyl’s distinct chatoyant effect, resembling a cat’s eye, sets it apart as a phenomenal gemstone. Its rarity, captivating optical phenomenon, and symbolic significance make it a treasured choice for gem enthusiasts and jewelry aficionados alike.
Gemstone Evaluation and Grading
Gemstone evaluation and grading involve assessing various factors that contribute to a gemstone’s overall quality and value. Different gem types may have specific grading criteria based on their unique characteristics. For chrysoberyl and its varieties like alexandrite and cat’s-eye chrysoberyl, the following factors are considered:
1. Color Grading and Factors:
Color is one of the most important factors in gemstone grading, as it significantly influences a gem’s appearance and value. For chrysoberyl varieties:
Hue: The dominant color present in the gem. In chrysoberyl, this can range from yellow and green to brown and colorless.
Saturation: The intensity or purity of the color. More saturated colors are generally preferred.
Tone: The darkness or lightness of the color. A balanced tone is often more desirable.
Color Change (Alexandrite): The degree of color change, the strength of each color, and the contrast between them are crucial factors in evaluating alexandrite.
2. Clarity Assessment:
Clarity refers to the presence of internal characteristics (inclusions) and surface features (blemishes) within the gemstone. Inclusions can vary in size, type, and location. In chrysoberyl and its varieties:
Cat’s-Eye Inclusions: For cat’s-eye chrysoberyl, the presence and quality of the silk inclusions that create the chatoyant effect are important. A sharp, centered, and well-defined cat’s-eye band enhances value.
Alexandrite Clarity: In alexandrite, clarity is assessed similarly to other gemstones. Gems with fewer and less noticeable inclusions are considered more valuable.
3. Cut and Proportions:
The cut of a gemstone refers to its shape, facet arrangement, and proportions. For chrysoberyl varieties:
Cat’s-Eye Cut: In cat’s-eye chrysoberyl, a smooth and symmetrical cabochon cut is preferred to showcase the chatoyant effect. The height and shape of the dome influence the visibility and sharpness of the cat’s-eye.
Alexandrite Cut: For alexandrite, a well-executed cut that maximizes color change and brilliance is important. Cutters often aim for a balance between showcasing color change and minimizing color loss.
4. Carat Weight:
Carat weight measures a gemstone’s size, with one carat equaling 200 milligrams. Larger gemstones are generally more valuable, but other factors like color, clarity, and quality of the optical phenomena also play a significant role.
Overall Quality and Value:
Gemstones are evaluated based on how well they combine these factors to create a visually appealing and valuable stone. A well-balanced combination of color, clarity, cut, and carat weight determines a gem’s overall quality and, consequently, its value in the market. Rarity and the presence of unique phenomena like color change and chatoyancy further enhance a gem’s desirability.
Gemstone evaluation is often performed by trained gemologists who use standardized grading systems to provide accurate and consistent assessments of a gemstone’s attributes. These assessments guide pricing, purchasing, and collecting decisions within the gemstone industry.
Chrysoberyl in the Jewelry Industry
Chrysoberyl, with its various color varieties and unique optical phenomena, holds a significant place in the jewelry industry. It is valued not only for its visual appeal but also for its durability and versatility. Here’s how chrysoberyl is used in the jewelry industry:
1. Gemstone Jewelry:
Chrysoberyl is used in a wide range of jewelry pieces, including rings, earrings, necklaces, bracelets, and pendants. Its vibrant colors and eye-catching optical phenomena make it a popular choice for both casual and formal jewelry designs.
Alexandrite Rings: Alexandrite, with its color-changing properties, is often featured in engagement and statement rings. The ability to display different colors under various lighting conditions adds an intriguing and dynamic aspect to jewelry pieces.
Cat’s-Eye Jewelry: Cat’s Eye Chrysoberyl is typically cut into smooth, rounded cabochons to showcase the cat’s-eye effect. These cabochons are commonly used in rings, pendants, and earrings, allowing the captivating phenomenon to be prominently displayed and admired.
2. Collector’s Items:
High-quality alexandrite and cat’s-eye chrysoberyl gemstones are prized by collectors for their rarity and unique optical phenomena. Collectors often seek stones with well-defined and intense color change or chatoyancy, as these qualities enhance the gem’s value.
3. Custom Jewelry Design:
Chrysoberyl’s range of colors and optical effects provides jewelry designers with opportunities to create custom pieces that highlight the gemstone’s unique qualities. Designers can play with metal choices, settings, and complementary gemstones to enhance the beauty of chrysoberyl.
4. Birthstone and Anniversary Jewelry:
Chrysoberyl’s yellow and green color varieties make it an alternative birthstone for the month of June. It can be used in jewelry pieces to celebrate June birthdays. Additionally, certain anniversaries are associated with chrysoberyl as a symbolic gift choice.
5. Investment Jewelry:
Rare and high-quality chrysoberyl gemstones, especially alexandrite, can appreciate in value over time due to their scarcity. Some individuals choose to invest in such gemstones as a form of alternative investment.
6. Museum and Exhibition Pieces:
Extraordinary chrysoberyl specimens, particularly those with exceptional color-changing or cat’s-eye effects, may find their way into museum collections and exhibitions, showcasing their rarity and aesthetic beauty.
7. Celebrity Endorsement:
When celebrities and public figures wear jewelry featuring unique gemstones like chrysoberyl, it can draw attention to these gemstones and increase their popularity in the fashion and jewelry industries.
In summary, chrysoberyl’s captivating colors, optical phenomena, and durability make it a valuable and sought-after gemstone in the jewelry industry. Its versatility allows it to be used in a variety of jewelry designs, from everyday wear to custom creations, and its rarity adds to its allure for collectors and enthusiasts alike.
Synthetic Chrysoberyl and Imitations
As with many valuable and sought-after gemstones, chrysoberyl has been imitated and synthesized to replicate its appearance. It’s important for consumers, gem enthusiasts, and jewelry professionals to be aware of these synthetics and imitations to ensure they are purchasing genuine and accurately represented gemstones. Here are some common considerations:
1. Synthetic Chrysoberyl:
Synthetic chrysoberyl is created in a laboratory setting using processes that simulate the conditions under which natural chrysoberyl forms. These synthetic stones can closely mimic the appearance of natural chrysoberyl, including color and optical phenomena. Some common methods for creating synthetic chrysoberyl include:
Flux Growth: This method involves dissolving chrysoberyl components in a flux and then allowing them to recrystallize under controlled conditions to form synthetic crystals.
Hydrothermal Synthesis: Hydrothermal chambers are used to create synthetic chrysoberyl crystals by growing them in a high-pressure, high-temperature environment similar to the conditions in which natural crystals form.
2. Imitations:
Imitations are materials that may look similar to chrysoberyl but are not true chrysoberyl. Some common imitations include:
Quartz Cat’s-Eye: Cat’s-eye quartz, which is often gray or brown, can be cut and polished to resemble cat’s-eye chrysoberyl. However, the chatoyant effect in quartz is not as sharp or distinct as in genuine cat’s-eye chrysoberyl.
Synthetic Spinel: Certain synthetic spinels may be used to imitate chrysoberyl’s appearance, particularly in its yellow or colorless varieties.
3. Identifying Synthetics and Imitations:
Laboratory Reports: Reputable gemological laboratories can provide detailed reports that include information about a gemstone’s origin, treatment, and identity. These reports can help confirm the authenticity of a chrysoberyl.
Visual Inspection: Gemologists can use their expertise to visually inspect gemstones for signs of synthetic or imitation materials. For example, some synthetics might exhibit growth features that are not present in natural stones.
Equipment: Gemological tools like microscopes, refractometers, and spectrometers can be used to analyze a gemstone’s physical and optical properties, aiding in the identification process.
4. Disclosure:
Ethical and reputable jewelers and sellers should transparently disclose whether a gemstone is natural, synthetic, or an imitation. This information is crucial for consumers to make informed purchasing decisions.
5. Educate Yourself:
If you are considering purchasing a chrysoberyl or any other gemstone, it’s important to educate yourself about the gem’s characteristics, pricing, and common treatments or enhancements. If in doubt, seek the assistance of a qualified gemologist or jeweler to help you evaluate the gemstone’s authenticity.
In summary, while synthetic chrysoberyl and imitations exist, proper education, disclosure, and expert guidance can help ensure that you are acquiring genuine chrysoberyl gemstones with the desired properties and value.
Recap of Key Points
Chrysoberyl Overview:
Chrysoberyl is a mineral and gemstone belonging to the beryl family.
Its name is derived from the Greek words for “gold” and “beryl,” reflecting its golden to greenish hues.
Types and Varieties:
Chrysoberyl comes in various types, including the color-changing alexandrite and the cat’s-eye chrysoberyl with its chatoyant effect.
Varieties include yellow, green, brown, colorless, and more.
Physical Properties:
Chrysoberyl is known for its hardness (8.5 on the Mohs scale) and durability.
It displays pleochroism, showing different colors from different angles.
Color change is a unique trait of alexandrite, caused by chromium in its crystal structure.
Geological Occurrence:
Chrysoberyl forms in pegmatite veins and metamorphic rocks.
Significant sources include Brazil, Sri Lanka, Russia, Madagascar, India, and other locations.
Color Grading and Factors:
Color grading involves assessing hue, saturation, and tone.
For alexandrite, the color change and contrast are critical.
Cat’s-eye chrysoberyl’s chatoyancy is a major factor in evaluation.
Clarity Assessment:
Clarity evaluates inclusions and blemishes, which affect transparency.
Cat’s-eye chrysoberyl’s silk inclusions create the chatoyant effect.
Cut and Proportions:
Cat’s-eye chrysoberyl is often cut into cabochons to display chatoyancy.
Alexandrite is cut to optimize color change and brilliance.
Chrysoberyl in Jewelry:
Chrysoberyl is used in rings, earrings, necklaces, and more.
Alexandrite and cat’s-eye chrysoberyl are popular choices for custom and collector’s jewelry.
Synthetics and Imitations:
Synthetic chrysoberyl is created in labs to replicate natural gemstones.
Imitations like quartz cat’s-eye and synthetic spinel resemble chrysoberyl’s appearance.
Identification involves gemological testing, visual inspection, and reputable sources.
Value and Rarity:
High-quality chrysoberyl gemstones, especially alexandrite, can be valuable due to their rarity and unique properties.
Proper education and gemological assessments are important for determining value.
Chrysoberyl’s diversity, beauty, and unique optical phenomena have made it a captivating gemstone with historical significance and lasting appeal in the world of jewelry and gem collecting.
Crystal of bicolor spodumene var. kunziteKunzite-NouristanSpodumene
Spodumene is a
pyroxene member of inosilicate mineral with chemical formula is LiAl(SiO3)2,
lithium aluminium. It can also be pink, lilac, or green. Crystals are
prismatic, flattened, and typically striated along their length. Gem varieties
of the mineral usually exhibit strong pleochroism. Spodumene is an important ore of lithium. It occurs in lithium-bearing
granitepegmatite dykes, often with other lithiumbearing minerals, such as
eucryptite and lepidolite. One of the largest single crystals of any mineral
ever found was a spodumene specimen from South Dakota, USA, 47 ft (14.3 m) long
and 90 tons in weight.
Ordinary low temperature form α-spodumen is found in the
monoclinic system, while high-temperature β-spodumen crystallizes in the
tetragonal apparatus. Ordinary α-spodumen is converted to β-spodumen at
temperatures above 900 ° C. The crystals are generally densely streaked
parallel to the main axis. Crystal faces are usually scraped and pitted with
triangular markings. (Wiki)
Name: From the
Greek for ash-colored, in allusion to its color.
Spodumen occurs in lithium-rich granite pegmatites, aplites
and gneisses. Related minerals are: quartz, albite, petalite, eucryptite,
lepidolite and beryl.
The obvious material has been used as a precious stone with
its kunzite and hiddenite varieties which have attracted attention with their
robust pleochroism for a long time. Resource locations include Afghanistan,
Australia, Brazil, Madagascar, Pakistan, Quebec in Canada, and North Carolina,
California in the USA.
Uses Area and Economic Importance
Spodumene is an essential supply of lithium to be used in ceramics,
cell phones and car batteries, medicine, Pyroceram and as a fluent substance.
it’s far extracted from spodumene with the aid of fusing in lithium acid.
World lithium production through spodumen is approximately
80,000 mt per year, mainly from the Greenbushes pegmatite of Western Australia
and some Chinese and Chilean sources. The Talison mine at Greenbushes in
Western Australia is reported to be the largest and the highest ore level at
2.4% Li2O (2012 figures).
Another important advantage that the spoiler has over the
more popular saltwater competitors is the purity of the lithium carbonate it
can produce. While all products used by the battery industry are at least 99.5%
lithium carbonate, the formation of the remaining 0.5% is important; High amounts
of iron, magnesium or other harmful materials make the brine less attractive
product.
Gemstone Varieties
Hiddenite: The
emerald green spodümen type is colored with chromium like emerald. Not all
green spodumens are tinted with chrome, which tends to have a lighter color and
is therefore not hidden.
Kunzite: Kunzite
is a colorful gemstone that changes from pink to lilac, with a small amount of
trace color and various spodumens of manganese colors. Some (not all) used for
gemstones are heated to increase the color of kunzite. Also, it is irradiated
frequently to improve color.
Triphane: Triphane
is a yellow Spodumene variety.
Distribution
From Uto, Sodermanland, and in the Varutrask
pegmatite, 15 km northwest of Skelleftea, Vasterbotten, Sweden.
In Finland, from near Kuortane, and in the
Tammela district.
In the USA, giant crystals in the Etta mine,
near Keystone, Pennington Co., and elsewhere in the Black Hills, South Dakota;
at Hiddenite, Alexander Co. and in the Foote mine, Kings Mountain, Cleveland
Co., North Carolina; from the Pala district, San Diego Co., California; and in
the Harding mine, Dixon, Taos Co., New Mexico.
From the Tanco mine, Bernic Lake, Manitoba,
Canada.
At the Urupuca mine, Itambacari, and at
Resplendor, Minas Gerais, Brazil.
From Mawi and Kantiva, Nuristan district, Laghman
Province, Afghanistan.
At Maharitra, Mt. Bity, and at Anjanabonoina,
Madagascar.
From Bikita, Zimbabwe. Many other minor
localities are known.
References
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].
Wikipedia contributors. (2019, March 21). Spodumene. In Wikipedia, The Free Encyclopedia. Retrieved 23:32, July 7, 2019, from https://en.wikipedia.org/w/index.php?title=Spodumene&oldid=888757472
Phlogopite is a
member of mica group family of phyllosilicates mineral. Color is a yellow,
greenish, or reddish-brown. It is the magnesium endmember of the biotite stable
answer series, with the chemical formulation KMg3AlSi3O10 (F, OH) 2. Iron
substitutes for magnesium in variable quantities main to the more commonplace
biotite with higher iron content. For physicaly and optical identification, it
shares most of the feature of biotite.
An extensive-unfold member of the mica group occurring
particularly in crystalline, dolomitic marbles associated with spinel, diopside
and members of the chondrodite organization. Redefined as the OH give up-member
via the IMA Mica Subcommittee in 1998.
Crystallography:
Monoclinic; prismatic. Usually in six-sided plates or in tapering prismatic
crystals. Crystals frequently large and coarse. Found also in foliated masses
PhlogopiteComposition: A hydrous potassium
magnesium aluminum silicate, KMg2Al2Si3Oio(OH)2. Usually contains about 3 percent
of fluorine and some iron.
Diagnostic Features:
Characterized by its micaceous cleavage and yellowish brown color. Distinguished
from muscovite by its decomposition in sulfuric acid and from biotite by its
lighter color. But it is impossible to draw a sharp distinction between biotite
and phlogopite.
PhlogopiteUses: Same as for muscovite; chiefly as
electrical insulator.
Phlogopite occurs as a product of metamorphism in
crystalline magnesium limestones or dolomitic marbles and is also found in
serpentine. Rarely found in igneous rocks. Notable localities are in Finland;
Sweden; Campolungo, Switzerland; Ceylon; Madagascar. In the United States found
chiefly in Jefferson and St. Lawrence Counties, New York. Found abundantly in
Canada in Ontario at North and South Burgess, and in various other localities
in Ontario and Quebec.
Distribution
Some localities for well-crystallized material include:
In the USA, from Antwerp and Natural Bridge, Jefferson Co., and Edwards and Pierrepont, St. Lawrence Co., New York; from Franklin, Sussex Co., New Jersey.
In Canada, large crystals from the Lacey mine, Frontenac Co., and in North and South Burgess Townships, Ontario; from near Perkin’s Mills, and elsewhere in Gatineau Co., Quebec.
In the Slyudyanka region, near Lake Baikal, Siberia, Russia.
At near Feset, Norway.
From Campolungo, near St. Gotthard, Ticino, Switzerland.
In the Val di Fassa, Trentino-Alto Adige, and on Monte Braccio, Val Malenco, Lombardy, Italy.
From Saharakara and Ampandrandava, Madagascar.
At Anxiety Point, Nancy Sound, New Zealand.
References
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].A
Beryl is a mineral composed of beryllium aluminium cyclosilicate, with the chemical formula Be3Al2(Si6O18). It belongs to the cyclosilicate mineral group, which is characterized by its unique arrangement of silicate tetrahedrons forming rings. Beryl is widely known for its stunning range of colors and its use as a gemstone in various forms, each with its own name based on its color. Some of the most famous varieties of beryl include emerald (green), aquamarine (blue-green), morganite (pink), and heliodor (yellow).
Morganite with Quartz on Cleavelandite
crystals of beryl var. gosheniteemeraldgolden berlyNagar (Nagir), Hunza Valley, Gilgit District, Northern Areas, PakistanRed Beryl, Wah Wah Mts, Beaver County, Utah, USA
Name: The name
beryl is of ancient origin, derived from the Greek word which was applied to
green gem stones.
BerylComposition: Beryllium aluminum
silicate, Be3Al2Si60i8. BeO = 14.0 per cent, A120 3 = 19.0 per cent, Si02 =
67.0 per cent. Small amounts of the alkali oxides, often in part consisting of
cesium oxide, frequently replace the beryllium oxide
Diagnostic Features:
Recognized usually by its hexagonal crystal , form and color. Distinguished
from apatite by greater hardness.
Similar Species:Euclase, Be2Al2(Si04)2(OH)2, and gadoliniie, Ye,Fe” Be2(Si04)202, are rare beryllium silicates.
Crystal Structure: Beryl has a hexagonal crystal structure, meaning it has six-fold rotational symmetry around its vertical axis. This crystal structure forms prismatic, elongated hexagonal crystals with a well-defined basal cleavage. The basic building blocks of beryl’s crystal structure are chains of interconnected silicate tetrahedra, which are arranged in rings. The chains run parallel to the crystal’s c-axis and are linked together by metal cations (beryllium and aluminium) and other atoms in various coordination states. This unique arrangement gives beryl its distinctive physical and optical properties.
Physical Properties: Beryl exhibits a range of physical properties that contribute to its value and popularity as both a gemstone and an industrial mineral:
Color: As mentioned earlier, beryl occurs in a variety of colors, each corresponding to a different variety. For example, emerald is green due to the presence of trace amounts of chromium or vanadium, while aquamarine is blue-green due to iron impurities.
Hardness: Beryl has a hardness of 7.5 to 8 on the Mohs scale, making it relatively durable and suitable for jewelry use. However, its hardness can vary slightly depending on the specific variety.
Luster: Beryl displays a vitreous (glassy) luster when cut and polished. This contributes to its gem-like appearance.
Transparency: Beryl is often transparent to translucent, allowing light to pass through and exhibit its internal features.
Refractive Index: Beryl’s refractive index varies depending on the specific variety and its composition. This property affects the way light is bent as it enters and exits the gemstone, influencing its brilliance and sparkle.
Cleavage: Beryl has distinct basal cleavage, which means it can break along flat surfaces parallel to its basal plane.
Density: The density of beryl varies depending on its composition and impurities, but it typically falls within the range of 2.63 to 2.90 g/cm³.
Optical Phenomena: Some varieties of beryl, like cat’s eye and asteriated beryl, can exhibit optical phenomena such as chatoyancy (cat’s eye effect) and asterism (star effect), adding to their visual appeal.
In addition to its use as gemstones, beryl has industrial applications due to its resistance to chemicals, high melting point, and electrical conductivity. It is used in electronics, aerospace, and defense industries for various purposes.
In summary, beryl is a cyclosilicate mineral with a hexagonal crystal structure and a variety of captivating colors. Its unique physical properties have made it a sought-after gemstone and a valuable material in various industries.
Beryl is a versatile mineral that comes in several varieties, each known for its distinct color and unique characteristics. Here are some of the most well-known beryl varieties based on color:
Emerald:
Color: Emerald is renowned for its deep green color, which is caused by trace amounts of chromium and/or vanadium in the crystal structure.
Distinctive Features: Emeralds often exhibit a rich green hue that is highly prized in the world of gemstones. Their color can range from bluish-green to yellowish-green. Inclusions are common in emeralds and are sometimes referred to as “jardin” (French for garden), adding to their character.
Aquamarine:
Color: Aquamarine is characterized by its pale blue to blue-green color, reminiscent of the clear waters of the sea.
Distinctive Features: The light blue or cyan hue of aquamarine is highly desirable. Some aquamarines may display a bluish-green color, and they often have a transparent appearance. Like other beryl varieties, they can contain inclusions, but these are usually less pronounced than those in emeralds.
Morganite:
Color: Morganite is known for its delicate pink to peachy-pink color, caused by traces of manganese.
Distinctive Features: Morganite’s soft pastel hues make it a popular choice in jewelry. Its color range can vary from light pink to deeper peach tones. The clarity and transparency of morganite are valued, and the gemstone is often cut into elegant and stylish faceted shapes.
Heliodor:
Color: Heliodor comes in shades of yellow to yellow-green.
Distinctive Features: The name “heliodor” is derived from the Greek words for “sun” and “gift,” referencing its sun-like color. The gemstone can range from pale yellow to vibrant yellow-green. Heliodor’s bright color and relatively good clarity make it a striking choice for jewelry.
Goshenite:
Color: Goshenite is the colorless variety of beryl, often used as a base for various treatments and as a diamond substitute.
Distinctive Features: Goshenite’s lack of color allows it to showcase the brilliance and sparkle of the gem’s natural transparency. It’s sometimes used as a less expensive alternative to diamonds and as a neutral backdrop for other colored gemstones.
Color: Red beryl is one of the rarest and most valuable beryl varieties, displaying vivid shades of red due to traces of manganese.
Distinctive Features: Red beryl’s intense red color and scarcity make it highly sought after by collectors and gem enthusiasts. It’s considered one of the rarest gemstones in the world.
These are just a few of the many beryl varieties that exist, each prized for its distinct color and qualities. The diversity of beryl’s colors and properties has contributed to its enduring popularity in both the world of gemology and the jewelry industry.
Gemstone Properties and Uses
Beryl as a Gemstone: Historical Significance and Cultural Relevance:
Beryl has a long history as a prized gemstone and holds cultural significance in various civilizations. In ancient times, beryl was considered a symbol of purity and protection. The green variety, emerald, was particularly revered by the Egyptians for its lush color, often associated with fertility and rebirth. Ancient Greeks also highly valued emeralds and believed they could provide foresight and enhance the ability to predict the future.
Factors Influencing Beryl’s Value as a Gem:
Several factors contribute to the value of beryl as a gemstone:
Color: The color of the beryl variety greatly influences its value. The most vibrant and saturated colors are often the most prized. For example, emeralds with a deep, intense green color and aquamarines with a clear, blue hue are highly sought after.
Clarity: Clarity refers to the presence of internal inclusions or external blemishes within the gem. Beryl gemstones with fewer visible inclusions are considered more valuable. However, some inclusions, like those in emeralds, are accepted as part of the gem’s character if they don’t significantly affect transparency.
Size: Larger beryl gemstones are rarer and command higher prices, especially in high-quality colors and clarity. The scarcity of large, top-quality beryl gems contributes to their value.
Cut: The way a beryl gemstone is cut and faceted significantly impacts its appearance and value. Skilled cutting enhances the gem’s brilliance, sparkle, and color display. The cut should also be appropriate for the gem’s color and optical properties.
Popular Uses in Jewelry and Ornamental Pieces:
Beryl, in its various colorful forms, is highly prized in the world of jewelry and ornamental design:
Rings: Beryl gemstones are often set as centerpieces in rings, particularly in engagement rings and cocktail rings. The durability and wide range of colors make them versatile choices.
Necklaces and Pendants: Beryl gemstones are set into necklaces and pendants to add a splash of color and elegance. Emeralds and aquamarines are frequently used in these pieces due to their popularity and timeless appeal.
Earrings: Beryl gems are set in earrings, either as studs, drops, or chandelier-style designs. The gems’ transparency and luster make them attractive choices for enhancing a person’s facial features.
Bracelets and Brooches: Beryl gemstones can also be found in bracelets and brooches, adding a touch of sophistication and color to formal and casual attire alike.
Ornamental Pieces: Beyond jewelry, beryl is used in ornamental pieces such as carvings, sculptures, and decorative objects. These pieces showcase the gemstone’s beauty and can be highly collectible.
In summary, beryl has a rich historical and cultural significance as a gemstone. Its value is influenced by factors such as color, clarity, size, and cut. Beryl gemstones are widely used in jewelry and ornamental pieces, offering a broad spectrum of colors and options for expressing personal style and enhancing aesthetics.
Beryl’s Industrial Applications:
Beryl’s unique properties, particularly its content of the element beryllium, make it valuable in several industrial sectors:
Electronics and Telecommunications: Beryl’s excellent thermal conductivity, low dielectric constant, and stability in high-frequency environments make it suitable for applications in electronics and telecommunications. It is used in microwave components, transistors, and integrated circuits.
Aerospace and Defense: Beryl’s combination of lightweight and high strength makes it desirable for aerospace and defense applications. It is used in manufacturing lightweight structural components, such as satellite mirrors and components for military aircraft.
Nuclear Industry: Beryl is used in certain nuclear reactor designs due to its low absorption cross-section for thermal neutrons. This property makes it useful in nuclear power generation and research reactors.
Medical Industry: Beryllium is used in the medical industry for X-ray windows and various medical imaging equipment due to its transparency to X-rays and gamma rays.
Automotive and Transportation: Beryl’s strength-to-weight ratio is advantageous in applications where weight reduction is critical. It can be used in lightweight components for vehicles and transportation systems.
Extracting Beryllium from Beryl:
Beryllium is a valuable element in industrial applications due to its desirable properties, including its low density, high melting point, excellent thermal conductivity, and exceptional strength-to-weight ratio. Beryllium is often used as an alloying element to improve the properties of other metals.
Beryllium extraction from beryl involves several steps:
Mining and Crushing: Beryl-bearing ores are mined, and the beryl crystals are extracted. The ore is then crushed into smaller particles to facilitate further processing.
Concentration: The crushed ore is subjected to concentration methods, often involving physical separation techniques such as gravity separation or flotation. This step is necessary to increase the beryllium content in the ore.
Chemical Processing: The concentrated ore undergoes chemical processing to extract beryllium compounds. One common method is the alkaline dissolution process, where the ore is treated with sodium hydroxide to form soluble beryllium hydroxide.
Purification and Conversion: The beryllium hydroxide solution is purified to remove impurities. It is then converted into beryllium fluoride through chemical reactions.
Electrolysis: Beryllium fluoride is then subjected to electrolysis, where beryllium metal is deposited at the cathode. This process allows for the extraction of pure beryllium.
Alloy Production: Beryllium is often alloyed with other metals, such as copper, to create beryllium-copper alloys. These alloys have exceptional electrical and thermal conductivity, making them valuable in various industries.
It’s important to note that beryllium extraction and processing require careful handling and environmental considerations due to the toxic nature of beryllium compounds. Strict safety measures are taken to protect workers and the environment during these processes.
Formation of Beryl and Geological Conditions
Beryl forms in pegmatites and hydrothermal veins, which are specific geological environments that provide the necessary conditions for its crystallization. Pegmatites are coarse-grained igneous rocks with exceptionally large crystals, and hydrothermal veins are mineral deposits formed from hot, mineral-rich fluids that migrate through fractures in the Earth’s crust. The formation of beryl requires specific elements, temperatures, and pressures:
Source of Elements: Beryl forms primarily from the elements beryllium, aluminum, and silicon. These elements need to be present in the geological environment in sufficient quantities.
High-Pressure Conditions: Beryl formation occurs at relatively high pressures within the Earth’s crust. This is typically deeper within the crust where hydrothermal fluids interact with existing minerals.
Hydrothermal Fluids: In hydrothermal systems, hot fluids rich in mineral components migrate through fractures in the rocks. These fluids are often enriched in beryllium, aluminum, and silicon, providing the necessary elements for beryl formation.
Temperature Gradient: The temperature gradient between the hot hydrothermal fluids and the surrounding rock allows for the precipitation and crystallization of minerals like beryl.
Time: Beryl formation is a slow process that occurs over long periods of time, as the hydrothermal fluids interact with the surrounding rocks and minerals.
Common Locations for Beryl
Beryl is found in various parts of the world, often associated with granite pegmatites and hydrothermal deposits. Some of the notable locations for beryl mining and occurrence include:
Emerald Deposits: High-quality emeralds are found in countries like Colombia, Zambia, Brazil, and Afghanistan. Colombia, in particular, is famous for its lush green emeralds.
Aquamarine Deposits: Aquamarine can be found in Brazil, Madagascar, Nigeria, and the United States (such as in Colorado and California).
Morganite Deposits: Morganite is commonly found in Brazil, Madagascar, Afghanistan, and certain parts of the United States.
Heliodor Deposits: Heliodor can be found in Brazil, Russia, Namibia, and parts of North America.
Goshenite Deposits: Goshenite, the colorless variety of beryl, is found in various locations, often alongside other beryl varieties.
Red Beryl (Bixbite) Deposits: Red beryl, one of the rarest beryl varieties, is primarily found in the Wah Wah Mountains of Utah, USA.
Other Varieties: Other beryl varieties like yellow beryl and greenish-yellow beryl can also be found in various locations around the world.
These deposits are often associated with specific geological formations and mineral-rich environments that are conducive to the formation of beryl crystals. The demand for beryl as gemstones and for industrial purposes has led to exploration and mining in these regions.
Beryl Synthetics and Treatments
Synthetic Beryl: Differences from Natural Beryl:
Synthetic beryl, also known as lab-grown or man-made beryl, is produced in a controlled laboratory environment through various methods, including hydrothermal synthesis and flux methods. These synthetic crystals share the same chemical composition and crystal structure as natural beryl, but there are several key differences between synthetic and natural beryl:
Origin: Synthetic beryl is created in a laboratory, whereas natural beryl forms through geological processes in the Earth’s crust over millions of years.
Inclusions: Natural beryl often contains inclusions, which are mineral or fluid inclusions trapped during its formation. In contrast, synthetic beryl is typically more inclusion-free due to the controlled conditions of its growth.
Color: Some synthetic beryl can exhibit color that is too perfect or uniform, lacking the natural variations and nuances seen in many natural beryl specimens.
Growth Patterns: Natural beryl can display growth patterns and characteristics specific to its geological origin. Synthetic beryl may lack these natural growth features.
Price: Synthetic beryl is generally less expensive than natural beryl, especially for high-quality specimens, due to the difference in rarity and origin.
Common Treatments and Enhancements:
Gemstones, including beryl, often undergo treatments and enhancements to improve their appearance or marketability. Some common treatments and enhancements applied to beryl and other gemstones include:
Heat Treatment: Heat treatment is a common method used to enhance the color of beryl. For example, heat can lighten the color of blue aquamarine or improve the color of yellow beryl.
Irradiation: Irradiation is used to alter the color of some beryl varieties. For example, yellow beryl can be irradiated to achieve a greenish hue resembling emerald.
Oil or Resin Impregnation: In the case of emeralds, natural fractures and inclusions are sometimes filled with oils or resins to improve clarity and enhance color. This practice has been used for centuries to improve the appearance of emeralds.
Surface Coating: Surface coatings or films can be applied to beryl gemstones to enhance color temporarily. However, such coatings are generally not durable and can be easily damaged.
Clarity Enhancement: Some treatments involve filling surface-reaching fractures or cavities with optically transparent materials to improve the gem’s clarity and appearance.
It’s important to note that treatments and enhancements should be disclosed when selling gemstones, as they can significantly affect a gem’s value, durability, and long-term appearance. The gemstone industry follows ethical practices by providing full disclosure of any treatments or enhancements applied to gemstones. Consumers should always inquire about the treatment status of a gemstone before making a purchase to ensure they are making an informed decision.
Famous Beryl Gemstones
Hooker Emerald
Beryl gemstones, with their captivating colors and unique properties, have been cherished throughout history. Here are some famous beryl gemstones that have left their mark:
Patricia Emerald: This stunning emerald is one of the largest and most famous emeralds in the world. Named after its owner, Patricia, the gem weighs approximately 632 carats and is prized for its rich green color and impressive size.
Hooker Emerald: Weighing around 75.47 carats, the Hooker Emerald is a well-known Colombian emerald. It was named after its owner, Tiffany & Co. Vice President Tiffany & Co., who donated the gem to the Smithsonian Institution.
Mogul Emerald: This historic emerald is a 217.80-carat gem that originated in Colombia and was later acquired by a Mughal ruler. The gem is inscribed with Islamic prayers and calligraphy and has a storied past.
Hirsch Aquamarine: Weighing 109.92 carats, the Hirsch Aquamarine is a notable aquamarine gemstone known for its intense blue color. It was named after Richard T. Hirsch, a gem enthusiast and philanthropist.
Red Beryl from the Ruby Violet Mine: Red beryl, also known as bixbite, is one of the rarest and most valuable gemstones. The Ruby Violet Mine in Utah, USA, has produced some of the finest red beryl specimens, which are highly sought after by collectors.
Maxixe Aquamarine: The Maxixe aquamarine is a rare type of aquamarine that displays a deep blue color. Unlike traditional aquamarines, the Maxixe aquamarine’s color can fade upon exposure to light, distinguishing it from its counterparts.
Stories and Legends:
Curse of the Hope Emerald: The Hope Emerald, a legendary 45.52-carat emerald, is said to be cursed due to its tumultuous history. It was allegedly stolen from a temple in India and went through various owners before finding its way into the hands of an ill-fated adventurer, Lord Francis Hope.
The Empress Josephine’s Emerald Tiara: The Empress Josephine, wife of Napoleon Bonaparte, owned an exquisite emerald and diamond tiara. This historic piece of jewelry showcases the allure of emeralds during the 19th century.
The Eye of Brahma: The Eye of Brahma is a legendary emerald that was reportedly stolen from a Hindu temple in India. According to folklore, this gem’s theft led to a curse, bringing misfortune to anyone who possessed it.
The Legend of the Aquamarine: In ancient lore, aquamarines were believed to be the treasure of mermaids, and sailors often carried them as talismans to ensure safe voyages and protection against sea monsters.
The Chalk Emerald: This impressive 37.82-carat emerald was once part of the collection of socialite and jewelry enthusiast Bunny Mellon. It’s said to have been found in Colombia in the 19th century and later became part of notable gem collections.
These stories and legends highlight the allure, intrigue, and mystique associated with beryl gemstones throughout history. Beryl’s captivating colors and cultural significance have led to a rich tapestry of tales that continue to captivate our imagination.
Distribution
Beryl is found in various parts of the world, often in specific geological environments that provide the necessary conditions for its formation. Some of the notable locations where beryl is commonly found include:
Colombia: Colombia is famous for producing some of the finest emeralds in the world. The Muzo and Chivor mines are particularly renowned for their lush green emeralds.
Brazil: Brazil is a major source of various beryl varieties, including emerald, aquamarine, morganite, and heliodor. The Minas Gerais region is known for producing high-quality beryl gemstones.
Zambia: Zambia is known for its vivid green emeralds, often characterized by their unique bluish undertones. The Kagem mine is a notable source of these emeralds.
Madagascar: Madagascar produces a wide range of beryl varieties, including aquamarine, morganite, and heliodor. The island is known for its vibrant gemstone deposits.
Nigeria: Nigeria is a significant producer of aquamarine, with deposits found in various regions of the country.
Afghanistan: Afghanistan is known for its high-quality emeralds and morganites. The Panjshir Valley is a notable source of emeralds.
Russia: The Ural Mountains in Russia have been a historical source of beryl gemstones, including aquamarine and heliodor.
United States: The United States has beryl deposits in various states. The Wah Wah Mountains in Utah are known for producing rare red beryl, while states like North Carolina, Colorado, and California have yielded aquamarine and other beryl varieties.
Namibia: Namibia is known for its production of high-quality aquamarine and heliodor, often found in pegmatites.
Pakistan: Pakistan is another source of fine emeralds, often found in the Swat Valley region.
Mozambique: Mozambique has become a significant producer of various colored gemstones, including aquamarine and tourmaline.
Tanzania: Tanzania is known for its aquamarine and other colored gemstones, including tanzanite.
These are just a few of the many locations around the world where beryl is found. Each region’s deposits may vary in terms of quality, color, and availability. Beryl’s wide distribution highlights its global significance in both the gemstone and industrial sectors.
Tremolite,Campolungo, Piumogna Valley, SwitzerlandTremolite from Franklin, Sussex Co., New Jersey, United States
Tremolite is a
silicate mineral and member of the amphibole group. Chemical formula is
Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2. A calcium magnesium silicate, tremolite
forms a solid-solution series with ferroactinolite, where iron substitutes in
increasing amounts for magnesium. The color of tremolite varies with increasing
iron content from colorless to white in pure tremolite to gray, gray-green,
green, dark green and nearly black in other specimens. Traces of manganese may
tint tremolite pink or violet. When well-formed, crystals are short to long
prisms. More commonly, tremolite forms unterminated bladed crystals, parallel
aggregates of bladed crystals, or radiating groups. Tremolite and actinolite
both form thin, parallel, flexible fibers up to 10 in (25 cm) in length, which
are used commercially as asbestos. Tremolite is known as nephritejade when it
is massive and fine-grained. The mineral is abundant and widespread. It is the
product of both thermal and regional metamorphism and is an indicator of
metamorphic grade because it converts to diopside at high temperatures (1,065°F/575°C
or above).
Fibrous Tremolite: one
of the six identified varieties of asbestos. About forty, 200 tons of tremolite
asbestos is mined yearly in India. it’s miles otherwise found as a contaminant.
Name: Tremolite
is derived from the Tremola Valley near St. Gothard, Switzerland. Actinolite
comes from two Greek words meaning a ray and stone, in allusion to its
frequently somewhat radiated habit.
Polymorphism &
Series: Forms a series with actinolite and ferro-actinolite
Mineral Group: Amphibole
(calcic) group: Mg=(Mg + Fe 2+) ¸ 0.90; (Na + K)A < 0.5; NaB < 0.67; (Ca
+ Na)B ¸ 1.34; Si ¸ 7.5.
Crystallography:
Monoclinic; prismatic. Crystals prismatic in habit; the prism faces make angles
of 56° and 124° with each other. The termination of the crystals is almost
always formed by the two faces of a low clinodome (Figs. 400 and 401).
Tremolite is often bladed and frequently in radiating columnar aggregates. In
some cases in silky fibers. Coarse to fine granular. Compact
TremoliteComposition: Ca2Mg5Si80 22 (0 H )2, is an end member of an isomorphous series. Iron may replace magnesium in part, and when present in amounts greater than 2 per cent, the mineral is called actinolite
TremoliteDiagnostic Features: Characterized by
slender prisms and good prismatic cleavage. Distinguished from pyroxenes by the
cleavage angle and from hornblende by lighter color.
Simple or multiple: common parallel to {100}, rarely
parallel to {001}
Optic Sign
Biaxial (-)
Birefringence
δ = 0.026
Relief
Moderate
Dispersion:
r < v weak
Occurrence of Tremolite
Tremolite is most frequently found in impure, crystalline,
dolomitic limestones where it has formed on the recrystallization of the rock
during metamorphism. It is also found in talc schists. Actinolite commonly
occurs in the crystalline schists, being often the chief constituent of
green-colored schists and greenstones. Frequently the actinolite of such rocks
has had its origin in the pyroxene contained in the igneous rock from which the
metamorphic type has been derived.
Tremolite Uses Area
The fibrous variety is used to some extent as asbestos
material. The fibrous variety of serpentine furnishes more and usually a better
grade of asbestos. The compact variety nephrite is used largely for ornamental
material by oriental peoples
Distribution
Notable localities include:
Campolungo Alp, Ticino, and Bristenstock, Uri,
Switzerland.
In the USA, from Pierrepont, Gouverneur,
Edwards, and Macomb, St. Lawrence Co., New York; at Franklin, Sussex Co., New
Jersey; and Lee, Berkshire Co., Massachusetts.
At Wilberforce, Ontario, Canada.
From Kozano, Badakhshan Province, Afghanistan.
At Lelatema, Tanzania.
In the Brumado mine, Bahia, Brazil.
References
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].
Al Naslaa Rock is a unique geological formation located in the deserts of Saudi Arabia. It is renowned for its striking appearance, characterized by a massive sandstone block that appears to be split cleanly in two, almost as if by a laser or some other precise cutting tool. This remarkable natural wonder has captivated the imaginations of scientists, geologists, and tourists alike due to its mysterious and seemingly impossible formation.
Al Naslaa Rock Formation
The rock is situated in the Tayma Oasis, which is part of the Tabuk region in northwestern Saudi Arabia. It is a relatively remote and arid area surrounded by the vast expanse of desert, and it has become a popular destination for those interested in geology, archaeology, or simply intrigued by the enigmatic beauty of Al Naslaa Rock.
The most intriguing aspect of this rock formation is the perfect and seemingly symmetrical split down the center, which has led to various theories and speculations about how it came to be. Some suggest natural processes like erosion and stress fractures, while others entertain the idea of human or extraterrestrial involvement. Despite the ongoing debates, Al Naslaa Rock continues to be a subject of fascination and wonder for anyone who encounters it.
The formation of Al Naslaa Rock is a subject of geological curiosity and debate. While there is no definitive explanation for its creation, several theories have been proposed to account for this unique natural wonder. Here are some of the leading hypotheses:
Natural Geological Processes: Many geologists believe that Al Naslaa Rock’s split and its striking appearance are primarily the result of natural geological processes. One prevailing theory suggests that the rock was formed from sandstone, which is known for its layering. Over millions of years, a combination of factors like erosion, weathering, and the shifting of tectonic plates might have caused stress fractures and the eventual cleaving of the rock along its natural fault lines. This process could have resulted in the rock splitting neatly in two.
Exogenic Factors: Wind, rain, and temperature variations can contribute to the weathering of rocks. It’s possible that Al Naslaa Rock’s split was exacerbated or facilitated by these external factors over an extended period. Wind-blown sand, for example, could have acted as an abrasive agent, gradually eroding the rock along the fault lines.
Tectonic Activity: The Tayma Oasis region where Al Naslaa Rock is located is not immune to tectonic activity. It’s conceivable that movements in the Earth’s crust and the forces of compression and tension have played a role in shaping the rock, causing it to eventually split.
Alternative Theories: Some more imaginative theories have emerged, suggesting that the rock’s split might be the result of human or even extraterrestrial intervention, though these ideas lack scientific support and are generally considered highly unlikely.
What makes Al Naslaa Rock stand out are its distinctive features:
Perfect Split: The most remarkable characteristic of Al Naslaa Rock is the precision and symmetry of its split. The two halves appear as though they were cut with remarkable accuracy, which adds to the rock’s mystique.
Balanced Position: Both halves of the rock stand upright and are perfectly balanced on small pedestals, defying the laws of gravity and equilibrium.
Remote Location: Al Naslaa Rock is situated in a relatively remote desert region, making it an isolated and awe-inspiring geological formation surrounded by vast arid landscapes.
Despite ongoing scientific inquiry, the formation of Al Naslaa Rock remains an enigmatic marvel, with its origins continuing to be the subject of both fascination and debate among geologists and enthusiasts.
Split Rock Mystery of Al Naslaa Rock
Al Naslaa Rock Formation
The enigmatic split in Al Naslaa Rock is a source of fascination and mystery, as it appears to have been cleaved with remarkable precision. Numerous theories have been proposed to explain this intriguing feature, although no single theory has been definitively proven. Here are some of the leading theories:
Natural Weathering and Erosion: Many geologists believe that the split in Al Naslaa Rock is the result of natural weathering and erosion over millions of years. Sandstone, the type of rock that Al Naslaa is composed of, is known for its layering and natural fault lines. It’s possible that a combination of wind, rain, temperature fluctuations, and geological forces caused stress fractures to develop along these existing lines, ultimately leading to the rock splitting neatly in two. This theory suggests that the precision of the split is due to the pre-existing weaknesses in the rock’s structure.
Tectonic Activity: The region in which Al Naslaa Rock is located has experienced tectonic activity. Some suggest that movements in the Earth’s crust, including compression and tension forces, could have contributed to the rock’s splitting. These geological forces might have accentuated existing weaknesses in the rock’s structure.
Frost Wedging: Frost wedging is a geological process where water seeps into cracks in rocks, freezes, and expands, causing the cracks to widen and potentially lead to the splitting of rocks. In the arid desert environment where Al Naslaa Rock is located, extreme temperature variations between night and day could have contributed to frost wedging, eventually causing the rock to split.
Human or Extraterrestrial Involvement: Some more speculative theories propose that the split in Al Naslaa Rock could have been created by human or extraterrestrial intervention. Proponents of these theories point to the precision of the split and the absence of clear geological evidence as reasons to consider alternative explanations. However, these ideas lack credible scientific support and are generally considered highly unlikely.
Rapid Water Erosion: Another theory suggests that rapid water erosion, such as a sudden and intense flash flood, may have contributed to the rock’s splitting. While this might explain the clean break, it doesn’t address the precise symmetry of the split.
Despite the various theories, the exact cause of the split in Al Naslaa Rock remains a subject of ongoing geological investigation and debate. It continues to be a captivating geological mystery, drawing the attention of scientists, geologists, and curious visitors who are intrigued by the rock’s extraordinary and precise division.
Ancient Petroglyphs
Petroglyphs and rock art can be found in the vicinity of Al Naslaa Rock, adding to the historical and cultural significance of the region. These ancient carvings and paintings provide valuable insights into the people who once inhabited or visited the area. While not as well-documented as some other rock art sites, such as those in the Sahara or North America, these petroglyphs near Al Naslaa Rock are an important part of the archaeological and cultural heritage of Saudi Arabia.
Historical Significance: The petroglyphs in the region around Al Naslaa Rock are believed to date back thousands of years, possibly to prehistoric times. They serve as a tangible link to the past, offering glimpses into the lives, beliefs, and activities of ancient people who once inhabited or passed through this area.
Cultural and Religious Depictions: Many of the petroglyphs feature depictions of animals, hunting scenes, and human figures. Some may also depict religious or spiritual symbols that were significant to the cultures that created them. These carvings and paintings are valuable for understanding the cultural and religious practices of ancient societies.
Astronomical and Geometric Symbols: Some of the petroglyphs may incorporate astronomical symbols or geometric patterns. These could have been used for navigation, tracking celestial events, or as part of rituals related to the sky and cosmos. Deciphering these symbols can shed light on the knowledge and practices of ancient astronomers and mathematicians.
Communication and Storytelling: Petroglyphs often served as a form of communication and storytelling for ancient people. They could depict important events, tales of conquests, or migrations. Researchers analyze these carvings to decipher the narratives and histories of the cultures that created them.
Cultural Diversity: The diversity of petroglyphs in the region indicates that various cultures and communities have contributed to this rich tapestry of rock art over time. Studying the different styles and subjects of the petroglyphs can provide insights into the interactions and exchanges between these groups.
Conservation and Preservation: The protection and preservation of these ancient petroglyphs are of paramount importance. Vandalism and natural wear and tear pose threats to their longevity. Saudi Arabia, like many other countries with rock art sites, is working to safeguard and document these valuable historical and cultural resources.
While the exact age and cultural affiliations of the petroglyphs near Al Naslaa Rock may still be topics of research and study, they are a testament to the enduring human desire to record and communicate their experiences, beliefs, and histories through art. These ancient carvings and paintings serve as a bridge connecting the modern world with the rich heritage of those who once inhabited the deserts of Saudi Arabia.
Tourism and Conservation
Al Naslaa Rock has indeed become a tourist attraction due to its unique and enigmatic geological features. Visitors from around the world are drawn to this remote desert location in Saudi Arabia to witness the remarkable split rock formation and the surrounding desert landscape. The influx of tourists has brought both opportunities and challenges, and efforts are in place to preserve and protect the site.
Tourism at Al Naslaa Rock:
Visitor Interest: The striking appearance and mystery surrounding Al Naslaa Rock have led to a growing interest in the site. Tourists, nature enthusiasts, geologists, and photographers are among those who visit the area to witness this natural wonder.
Local Economy: The increasing popularity of Al Naslaa Rock has contributed to the local economy, as it provides opportunities for tourism-related businesses, such as tour guides, accommodations, and restaurants, to thrive in the region.
Conservation and Protection Efforts:
Access Control: To protect the site from over-tourism and potential vandalism, access to Al Naslaa Rock is often controlled. Visitors may need to obtain permits or be accompanied by authorized guides to access the area. This helps manage the number of people visiting the site and minimizes potential harm.
Educational Initiatives: Local authorities and conservation organizations often engage in educational programs to raise awareness about the importance of preserving Al Naslaa Rock and its surroundings. These programs may target both locals and tourists, emphasizing responsible and respectful behavior.
Infrastructure Development: Constructing well-maintained pathways, viewing platforms, and other visitor facilities can help reduce environmental impact by concentrating foot traffic and preventing erosion around the rock. Proper infrastructure also enhances the visitor experience.
Regulations and Enforcement: Regulations may be put in place to prohibit activities that could harm the site, such as climbing on or defacing the rock. Enforcement of these regulations is essential to discourage destructive behavior.
Monitoring and Research: Consistent monitoring and research into the geological and environmental conditions of Al Naslaa Rock and its surroundings can inform conservation efforts. Understanding how natural processes and human impact affect the site is critical for preservation.
Collaboration with Indigenous Communities: Working closely with indigenous or local communities in the area is vital. Their knowledge of the land, cultural significance, and historical context of the site can contribute to responsible management and conservation efforts.
Sustainability Initiatives: Promoting sustainable tourism practices, such as waste management and eco-friendly accommodations, can minimize the ecological footprint of visitors and contribute to long-term preservation.
Balancing tourism and conservation at Al Naslaa Rock is an ongoing challenge. While tourism can bring economic benefits to the region, it must be managed carefully to protect the geological wonder and the fragile desert ecosystem. Collaborative efforts among government authorities, local communities, and conservation organizations are essential to ensure that Al Naslaa Rock remains a natural treasure for future generations to appreciate and study.
Cultural and Mythological Significance of Al Naslaa Rock
Al Naslaa Rock holds cultural and mythological significance, particularly among indigenous peoples in the region. While it may not have a well-documented mythology like some other natural landmarks, its unique appearance and location in the desert have likely led to various local beliefs and stories. Here are some aspects of its cultural and mythological significance:
Local Folklore: In desert regions, large rock formations often feature in local folklore and legends. Al Naslaa Rock may have been the subject of such stories, passed down through generations. These stories might explain the split in the rock or attribute it to supernatural or mythological forces.
Symbolic Significance: The striking appearance of Al Naslaa Rock, with its two perfectly balanced halves, could have symbolic significance in local cultures. It might represent ideas of balance, unity, or duality, and be incorporated into rituals or ceremonies.
Possible Archaeological Significance: While not confirmed, the area around Al Naslaa Rock could have archaeological sites that hold cultural significance. These sites may contain artifacts, petroglyphs, or inscriptions that provide clues about the beliefs and practices of the ancient people who inhabited the region.
Astronomical and Navigational Uses: The rock’s unique geometry could have made it a valuable landmark for indigenous peoples for navigation or astronomical observations. It might have been used to mark certain celestial events or to guide travelers in the desert.
Cultural Identity: Al Naslaa Rock could hold cultural significance as a point of identification and pride for the local community. It may be considered a symbol of the region and its history.
Pilgrimage or Ritual Sites: There is the possibility that Al Naslaa Rock or the surrounding area was used as a site for rituals, ceremonies, or even pilgrimage by indigenous cultures. The rock’s unique features could have been seen as sacred.
Sacred Geometry: Some cultures ascribe spiritual or mystical significance to geometric patterns and shapes. The symmetry and precision of the rock’s split may have been seen as embodying sacred geometry principles.
It’s important to note that the exact cultural and mythological significance of Al Naslaa Rock may not be well-documented or widely known, and these aspects can vary among different indigenous groups or communities in the region. Further research and cultural studies could provide deeper insights into the significance of this remarkable geological formation in the local and regional context.
Scientific Research
Scientific research on Al Naslaa Rock has primarily focused on understanding its geological attributes, formation, and the unique features that make it stand out. While the exact origins of this rock formation remain a subject of debate, several scientific studies and investigations have provided valuable insights into its history. Here are some key points:
Geological Studies: Numerous geologists have conducted fieldwork and geological surveys in the vicinity of Al Naslaa Rock. They have examined the rock’s composition, its layering, and the surrounding geological context. These studies have aimed to determine the most likely natural processes that led to the rock’s split.
Dating Techniques: To estimate the age of Al Naslaa Rock and its surroundings, scientists have employed various dating techniques. Radiocarbon dating, optically stimulated luminescence (OSL), and other methods have been used to determine when certain geological events, like erosion, occurred.
Structural Analysis: The precision of the split in Al Naslaa Rock has led to in-depth structural analyses. Researchers have looked at the orientation of the rock’s bedding planes and fractures to better understand the forces that may have caused the split. They’ve also examined the symmetry and balance of the two halves.
Climate and Erosion Studies: Studies on the local climate, including temperature fluctuations, wind patterns, and precipitation, have been conducted to assess their role in weathering and erosion in the region. Researchers have explored whether rapid weathering events, like frost wedging, could have contributed to the rock’s formation.
Simulation and Modeling: Computer modeling and simulations have been used to test various hypotheses about the rock’s formation. By simulating the effects of different geological processes and forces, researchers have tried to replicate the unique features of Al Naslaa Rock.
Cultural and Historical Research: In addition to geological studies, there has been some research into the cultural and historical context of the region, which could provide insights into the indigenous peoples who may have interacted with the rock and any potential cultural or ritual significance.
It’s worth noting that scientific consensus on the formation of Al Naslaa Rock has not been fully established. The debate continues, and new research and studies may provide further insights into this intriguing geological wonder. While Al Naslaa Rock remains a geological mystery, it also serves as a testament to the curiosity and dedication of the scientific community in unraveling the secrets of the Earth’s natural history.
Comparisons with Other Geological Wonders
Al Naslaa Rock is a unique and intriguing geological wonder, but it’s not the only remarkable rock formation on our planet. Here are some comparisons between Al Naslaa Rock and other famous geological formations:
Location: Al Naslaa Rock is located in Saudi Arabia, while Uluru is in Australia’s Northern Territory.
Composition: Al Naslaa Rock is a sandstone formation, whereas Uluru is a massive sandstone monolith.
Appearance: Both formations are striking but different. Al Naslaa Rock is known for its perfect split, while Uluru is known for its massive size, rich red color, and cultural significance to the Indigenous Anangu people.
Al Naslaa Rock vs. The Wave:
Location: Al Naslaa Rock is in Saudi Arabia, whereas The Wave is found in the Vermilion Cliffs National Monument in the United States.
Formation: Al Naslaa Rock is a split sandstone formation, while The Wave is a sandstone rock feature with wave-like, undulating patterns.
Accessibility: Al Naslaa Rock is relatively remote and requires permits, while The Wave is a popular hiking destination with limited permits issued daily.
Location: Al Naslaa Rock is in the desert of Saudi Arabia, while the Giant’s Causeway is situated on the coast of Northern Ireland.
Formation: Al Naslaa Rock is a sandstone split, while the Giant’s Causeway is an area of interlocking basalt columns, formed by volcanic activity.
Geological Processes: Al Naslaa Rock’s formation is debated, with some suggesting natural weathering, while the Giant’s Causeway’s formation is well-understood and attributed to volcanic activity.
Location: Al Naslaa Rock is in Saudi Arabia’s desert, while Mount Rushmore is located in the Black Hills of South Dakota, USA.
Formation: Al Naslaa Rock is a natural sandstone formation, whereas Mount Rushmore is a sculpture carved into the granite face of a mountain.
Significance: Mount Rushmore is famous for its enormous sculpted presidential faces, representing U.S. history, whereas Al Naslaa Rock is renowned for its natural geological features.
Location: Al Naslaa Rock is in Saudi Arabia’s desert, while the Grand Canyon is a massive canyon located in the southwestern United States.
Formation: Al Naslaa Rock is a single rock formation, while the Grand Canyon is a vast geological wonder created by the Colorado River’s erosion over millions of years.
Scale: The Grand Canyon is on a much larger scale, both in terms of size and geological complexity.
These comparisons illustrate the diversity of geological wonders found around the world, each with its unique characteristics, formation processes, and cultural significance. While Al Naslaa Rock stands out for its perfect split and enigmatic origin, other formations captivate the world with their own distinct features and histories.
Visiting Al Naslaa Rock
Visiting Al Naslaa Rock can be a fascinating and unique experience, but it’s important to be prepared as the site is situated in a remote desert area in Saudi Arabia. Here’s some practical information for travelers who want to visit:
How to Get There:
Location: Al Naslaa Rock is located in the Tayma Oasis, which is part of the Tabuk region in northwestern Saudi Arabia.
Travel Restrictions: Check for current travel restrictions and visa requirements for Saudi Arabia before planning your trip. The rules and regulations can change, so it’s essential to stay updated.
Access Permit: Visitors typically require a permit to access the site. Obtain the necessary permits through local authorities or tour operators well in advance of your trip.
Local Guide: It’s advisable to hire a local guide who knows the area and can assist with navigation and interpretation of the site’s features.
What to Expect:
Remote Location: Al Naslaa Rock is in a remote desert area with little infrastructure. Be prepared for a lack of amenities like restrooms or restaurants in the immediate vicinity.
Extreme Climate: The desert climate can be extreme, with scorching temperatures during the day and cooler nights. Be sure to carry sufficient water, sunscreen, a hat, and suitable clothing for sun protection.
Sandy Terrain: The area around Al Naslaa Rock may have soft, sandy terrain. Sturdy and comfortable footwear is essential for navigating the desert landscape.
Cultural Sensitivity: Respect local customs and traditions when visiting Saudi Arabia. Dress modestly, particularly in conservative regions, and adhere to cultural norms.
Lodging: Accommodations may be limited in the immediate area. You may need to stay in nearby towns or cities and plan a day trip to Al Naslaa Rock.
Safety: Pay attention to safety guidelines provided by your local guide or authorities. Be cautious when exploring the rocky terrain to avoid falls or injury.
Photography: Al Naslaa Rock is a popular subject for photographers. Be sure to bring your camera equipment and consider the best time of day for capturing the rock’s features in optimal lighting conditions.
Preservation: Be mindful of the need to protect the site and its surroundings. Avoid climbing on or defacing the rock, and follow any specific conservation guidelines provided.
Visiting Al Naslaa Rock offers a unique opportunity to witness a geological wonder in a remote desert setting. While the journey can be challenging, the experience is well worth it for those intrigued by this remarkable split rock formation and its mysterious origins. Remember to plan your trip carefully, obtain the necessary permits, and respect the local culture and environment.
Acanthite from Freiberg dist., Erzgebirge, Saxony, GermanyAcanthite with Polybasite, Freiberg District, Erzgebirge, Saxony, Germany.Acanthite – Chispas Mine, Arizpe, Sonora, Mexico
Acanthite is a form of silver sulfide with the chemical formula: Ag2S. It crystallizes inside the monoclinic gadget and is the solid form of silver sulfide under 173 °C (343 °F). A silver sulfide, it is the maximum important ore of silver. It additionally happens in huge form and has an opaque, grayish black color. Above 350°F (177°C), silver sulfide crystallizes in the cubic machine, and it was assumed that cubic silver sulfide, known as argentite changed into a separate mineral from acanthite. it’s miles now known that they may be the identical mineral, with acanthite crystallizing within the monoclinic system at temperatures beneath 350°F (177°C). Acanthite forms in hydrothermal veins with other minerals, which includes silver, galene, pyrargyrite, and proustite. It also paperwork as a secondary alteration made from number one silver sulfides. when heated, acanthite fuses quite simply and releases sulfurous fumes. The maximum famous locality of acanthite, the Comstock Lode in Nevada, united states of america, turned into so wealthy in silver that a department of the usa mint was established at close by Carson city to coin its output.
Name: From the
Greek for thorn, in allusion to the shape of the crystals.
Polymorphism &
Series: The high-temperature cubic form (“argentite”) inverts to acanthite
at about 173 ◦C; below this temperature acanthite is the stable phase and forms
directly
Crystallography:
Isometric; hexoctahedral. Crystals most commonly show the cube, octahedron, and
dodecahedron, but are frequently distorted and arranged in branching or
reticulated groups. Most commonly massive, or as a coating.
AcanthiteComposition: Silver sulfide, Ag2S. Ag =
87.1 per cent, S = 12.9 per cent.
Diagnostic Features:
Argentite can be distinguished by its color, sectility, and high specific
gravity.
Primary
crystals rare, prismatic to long prismatic, elongated along [001], may be
tubular; massive. Commonly paramorphic after the cubic high-temperature phase
(“argentite”), of original cubic or octahedral habit
Polysynthetic on {111}, may be very complex due to
inversion; contact on {101}
Occurrence of Acanthite
Argentite is an critical primary silver mineral found in
veins related to local silver, the ruby silvers, polybasite, stephanite,
galena, and sphalerite. it could also be of secondary starting place. it’s
miles located in microscopic inclusions in so-called argentiferous galena.
Argentite is an important ore in the silver mines of Guanajuato and some place
else in Mexico; in Peru, Chile, and Bolivia. vital ecu localities for its
prevalence are Freiberg in Saxony, Joachimsthal in Bohemia, Schemnitz and
Kremnitz in Czechoslovakia, Kongsberg in Norway. in the united states of
america it’s been an important ore mineral in Nevada, appreciably on the
Comstock Lode and at Tonopah. it’s also found in the silver districts of
Colorado, and in Montana at Butte related to copper ores.
Acanthite Uses Area
An important ore of silver
This mineral has aesthetic price and is precious
because of its shortage.
it may be an effective manner of decreasing
steel availability and toxicity in infected soils.
• 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].
Chromite is an oxide mineral that an ironchromium oxide with formula: FeCr2O4. It is belonging to the spinel group. Chromite is the most important ore of chromium. Crystals are uncommon, but when found they are octahedral. Chromite is usually massive or in the form of lenses and tabular bodies, or it may be disseminated as granules. It is sometimes found as a crystalline inclusion in diamond. Chromite is dark brown to black in color and can contain some magnesium and aluminum. Chromite is most commonly found as an accessory mineral in iron- and magnesium-rich igneous rocks or concentrated in sediments derived from them. It occurs as layers in a few igneous rocks that are especially rich in iron and magnesium. Almost pure chromite is found in similar layers in sedimentary rocks. The layers are preserved when the sedimentary rocks metamorphose to form serpentinite. Referred to as chromitites, these rocks are the most important ores of chromium. The weathering of chromite ore bodies can also lead to its concentration in placer deposits.
Polymorphism &
Series: Forms series with magnesiochromite and hercynite.
ChromiteComposition: FeCr20 4. FeO = 32.0 per
cent, Cr20 3 = 68.0 per cent. The iron may be replaced by magnesium, and the
chromium by aluminum and ferric iron.
Diagnostic Features:
The submetallic luster usually distinguishes chromite, but the green borax bead
is diagnostic
Mineral Group: Spinel
group.
Crystallography:
Isometric; hexoctahedral. Habit octahedral. Crystals small and rare. Commonly
massive, granular to compact.
Environment: In
metamorphic Serpentine deposits, and also in ultrabasic igneous rocks, and in
placer deposits. May also occur in meteorites.
A cumulus mineral in ultramafic portions of layered mafic
igneous rocks; an accessory mineral in alpine-type peridotites; also detrital.
Common in all meteorites, except carbonaceous chondrites, and in lunar mare
basalts.
Chromite is a common constituent of peridotite rocks and the
serpentines derived from them. One of the first minerals to separate from a
cooling magma; large chromite ore deposits are thought to have been derived by
such magmatic differentiation.
The important countries for its production are New
Caledonia, Southern Rhodesia, Greece, U.S.S.R., and Canada. Found only
sparingly in the United States. Pennsylvania, Maryland, North Carolina, and
Wyoming have produced it in the past. California is the only important
producing state at present (1940). Also found in the Philippine Islands.
Chromite Uses Area
The only ore of chromium. Chromium is used with various other
metals to give hardness to steel, also as a plating material because of its
non-corrosive nature. Chromite bricks are used to a considerable extent as
linings for metallurgical furnaces, because of their neutral and refractory
character. The bricks are usually made of crude chromite and coal tar but
sometimes of chromite with kaolin, bauxite, or other materials. Chromium is a
constituent of certain green, yellow, orange, and red pigments and of similarly
colored dyes.
Distribution
Widespread. From Gassin, Var, France.
Large crystals from Hangha, Sierra Leone.
At Tiebaghi, New Caledonia.
As economic deposits in: the Bushveld complex,
Transvaal, South Africa.
From the Great Dyke, Zimbabwe.
From many localities in Turkey.
At Saranay and elsewhere in the Ural Mountains,
Russia.
• 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].
“Alma King”, largest known rhodochrosite crystal, Denver Museum of Nature and ScienceRhodochrosite with Fluorite,Tetrahedrite, QuartzRhodochrosite, from the Sweet Home Mine, Colorado, private collection
Rhodochrosite is a carbonate mineral with formula: MnCO3. It has a classic rose-pink color, but specimens can also be brown or gray. It forms dogtooth or rhombohedral crystals like calcite, but it may also occur in stalactitic, granular, nodular, botryoidal, and massive habits. Rhodochrosite is found in hydrothermal ore veins with sphalerite, galena, fluorite, and manganese oxides. It also occurs in metamorphic deposits and as a secondary mineral in sedimentary manganese deposits. Abundant at Butte, Montana, and other localities, rhodochrosite is sometimes mined as an ore of manganese.
Name: Derived
from two Greek words meaning rose and color, in allusion to its rose-pink
color.
Polymorphism &
Series: Forms two series, with calcite and with siderite.
Mineral Group: Calcite
group.
RhodochrositeComposition: Manganese carbonate,
MnC03. MnO = 61.7 percent, C02 = 38.3 percent. Iron is usually present,
replacing a part of the manganese, and some analyses report calcium, magnesium,
zinc.
Diagnostic Features:
Told usually by its pink color, rhombohedral cleavage, and hardness (4).
Distinguished by its hardness from rhodonite (MnSi03, H. = 5, 5-6, 5).
Crystallography:
Rhombohedral; scalenohedral. Only rarely in crystals of the unit rhombohedron;
frequently with curved faces. Usually cleavable massive; granular to compact.
Environment: Hydrothermal
veins associated with Silver, Copper, and lead sulfides; may also be found in
some pegmatites.
Pink,
rose, red, yellowish-grey, brown, white, gray; colourless to pale rose in
transmitted light.
Streak
White
Luster
Vitreous,
Pearly
Cleavage
Perfect
On {1011}.
Diaphaneity
Transparent, Translucent
Mohs Hardness
3,4 – 4
Crystal System
Trigonal
Tenacity
Brittle
Density
3.7 g/cm3 (Measured) 3.7 g/cm3 (Calculated)
Fracture
Irregular/Uneven, Conchoidal
Parting
On {0112} at times.
Crystal habit
Rhombohedral and scalenohedral crystals; also
commonly bladed, columnar, stalactitic, botryoidal, granular or massive
Rhodochrosite Optical Properties
Color / Pleochroism
Weak
RI
values:
nω = 1.814 – 1.816 nε = 1.596 – 1.598
Twinning
On {1012} as contact and lamellar
Optic Sign
Uniaxial (-)
Birefringence
δ = 0.218
Relief
High
Occurrence of Rhodochrosite
A primary mineral in low- to moderate-temperature
hydrothermal veins; in metamorphic deposits; common in carbonatites; authigenic
and secondary in sediments; uncommon in granite pegmatites.
Rhodochrosite is a comparatively rare mineral, occurring in
veins with ores of silver, lead, and copper, and with other manganese minerals.
Rhodochrosite Uses Area
Its primary use is as ore of manganese, which is
a key part of minimal effort treated steel definitions and certain aluminum
amalgams.
Quality banded examples are frequently utilized
for decorative stones and jewelry. Because of its being moderately delicate,
and having flawless cleavage, it is exceptionally hard to cut, and along these
lines seldom discovered faceted in gems.
Manganese carbonate is incredibly ruinous to the
amalgamation procedure utilized in the convergence of silver minerals, and were
frequently disposed of on the mine dump.
Distribution
Numerous localities; only a few for fine specimens are
listed.
From Cavnic (Kapnikbanya) and Herja (Kisbanya),
Baia Mare (Nagyb´anya) district, Romania.
In the Wolf mine, near Herdorf, Westphalia,
Germany.
In Russia, from the Vuoriyarvi carbonatite
complex and the Kovdor massif, Kola Peninsula.
Large twinned crystals at Mont Saint-Hilaire,
Quebec, Canada.
In the USA, from the Emma mine, Butte, Silver
Bow Co., Montana; in Colorado, at many localities, as fine large crystals in
the Home Sweet Home mine, Alma, Park Co., from the Climax mine, Lake Co., in
the Sunnyside mine, near Silverton, San Juan Co., and the Mountain Monarch
mine, Ouray Co.
In Mexico, from Cananea, Sonora, and Santa
Eulalia, Chihuahua. Large crystals from the Huallapon mine, Pasto Bueno, Ancash
Department, and in the Uchuc-Chacua deposit, Cajatambo Province, Peru.
In Province, Peru.
A large deposit of ornamental banded material at
the Capillitas mine, San Luis, Catamarca Province, Argentina.
Exceptional crystals from the Hotazel and
N’Chwaning mines, near Kuruman, Cape Province, South Africa.
From the Inakuraishi and Yakumo mines, Hokkaido,
Japan.
References
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].
