Hematite

Hematite is a mineral and a common form of iron oxide. It is known for its distinctive reddish-brown to black metallic luster. The name “hematite” is derived from the Greek word “haima,” which means blood, due to its reddish color when it is powdered or in a fine-grained form.

Hematite has a chemical formula Fe2O3, indicating that it consists of two iron (Fe) atoms bonded to three oxygen (O) atoms. It has a high iron content and is one of the most abundant iron ores found on Earth. It is often found in sedimentary, metamorphic, and igneous rocks.

One of the notable characteristics of hematite is its streak. When hematite is scratched on a rough surface, it leaves a reddish-brown streak, which distinguishes it from other similar-looking minerals. This streak is a useful identification feature for hematite.

Hematite has been used by humans for thousands of years due to its distinctive properties. It has been utilized as a pigment, producing a reddish color in paints and dyes. Additionally, hematite is a significant source of iron ore and has been mined for its iron content. Iron extracted from hematite is used in the production of steel, transportation, construction, and various industrial applications.

In addition to its practical uses, hematite is also appreciated for its metaphysical properties. It is believed to have grounding and protective qualities, promoting strength, courage, and vitality. Some people use hematite as a stone for meditation, believing it helps in focusing and balancing energy.

Overall, hematite is a versatile mineral with a long history of human usage. Whether it’s for its industrial applications, artistic purposes, or metaphysical properties, hematite continues to be valued and appreciated for its unique characteristics.

It is black or silver gray, brown to reddish brown or red. There are several varieties. Among them; kidney ore, martite, iron rose. There are different forms, however, all of them have a rust red line. It is harder than pure iron, but it can break quickly.

Mineral Group: Hematite group.

Name: From the Greek for blood, in allusion to its color.

Polymorphism & Series: Dimorphous with maghemite.

Association: Ilmenite, rutile, magnetite (metamorphic and igneous); goethite, siderite, lepidocrocite (sedimentary).

Chemical Properties of Hematite

Hematite, with the chemical formula Fe2O3, exhibits several chemical properties that contribute to its characteristics and behavior. Here are some of the key chemical properties of hematite:

1. Composition: Hematite consists of iron (Fe) and oxygen (O) atoms, with two iron atoms bonded to three oxygen atoms in each formula unit (Fe2O3).
2. Iron Content: Hematite is a rich source of iron, typically containing about 70% iron by weight. This high iron content makes it an important ore for iron extraction and steel production.
3. Crystal Structure: Hematite crystallizes in the trigonal crystal system, forming rhombohedral crystals. Its crystal structure consists of close-packed oxygen atoms with iron ions occupying interstitial positions.
4. Stability: Hematite is a stable compound under normal conditions. It is resistant to chemical weathering and remains relatively unchanged over long periods of time.
5. Redox Properties: Hematite can undergo redox reactions, meaning it can both give and accept electrons. It can be reduced to form magnetite (Fe3O4) or metallic iron in the presence of reducing agents.
6. Magnetic Properties: Pure hematite is not magnetic, but certain hematite specimens may exhibit weak magnetism due to the presence of small amounts of magnetite impurities. These magnetic hematite samples are often used in jewelry and therapeutic applications.
7. Acid-Base Behavior: Hematite is insoluble in water and most acids. It is stable and unaffected by weak acids like dilute hydrochloric acid or sulfuric acid. However, concentrated acids and strong alkalis can attack and dissolve hematite over time.
8. Reactivity: Hematite can react with various chemicals under appropriate conditions. For example, it can react with carbon monoxide (CO) to produce iron metal and carbon dioxide (CO2) in the process known as the reduction of hematite.

These chemical properties contribute to the unique behavior and applications of hematite in various fields, including industry, geology, and materials science.

Physical Properties of Hematite

Color	Metallic gray, dull to bright red
Streak	Bright red to dark red
Luster	Metallic to splendent
Cleavage	None
Diaphaneity	Opaque
Mohs Hardness	6.5
Specific Gravity	5.26
Diagnostic Properties	Magnetic after heating
Crystal System	Trigonal
Parting	Partings on {0001} and {1011} due to twinning. Unique cubic parting in masses and grains at Franklin Mine, Franklin, NJ.
Tenacity	Brittle
Fracture	Irregular/Uneven, Sub-Conchoidal
Density	5.26 g/cm3 (Measured)    5.255 g/cm3 (Calculated)

Optical Properties of Hematite

Type	Anisotropic
Anisotropism	Distinct
Color / Pleochroism	brownish red to yellowish red
Twinning	Penetration twins on {0001}, or with {1010} as a composition plane. Frequently exhibits a lamellar twinning on {1011} in polished section
Optic Sign	Uniaxial (–)
Birefringence	δ = 0.280
Relief	Very High

Occurrence and natural sources

Hematite occurs in a variety of geological settings and is one of the most abundant iron-bearing minerals found on Earth. It is widely distributed and can be found in different types of rocks and deposits. Here are some of the natural sources and occurrences of hematite:

1. Sedimentary Deposits: Hematite is commonly found in sedimentary rocks, especially those of chemical or biochemical origin. It forms as a precipitate from water solutions or as a result of chemical reactions in aqueous environments. Sedimentary deposits of hematite can occur in banded iron formations (BIFs), which are important sources of iron ore.
2. Hydrothermal Veins: Hematite can also be found in hydrothermal veins, which are formed when hot fluids rich in minerals migrate through fractures in rocks and deposit minerals. In these settings, hematite can form along with other minerals such as quartz, calcite, and sulfides.
3. Contact Metamorphism: Hematite can be formed through contact metamorphism, which occurs when rocks are subjected to high temperatures and low-pressure conditions near igneous intrusions. The heat from the intrusion alters the surrounding rocks, leading to the formation of hematite veins or nodules.
4. Weathering and Erosion: Hematite can be formed as a result of weathering and erosion of iron-bearing rocks. When iron-rich minerals in rocks are exposed to oxygen and water over time, they can oxidize and transform into hematite. This process is commonly observed in soil profiles and weathered outcrops.
5. Martian Hematite: Hematite has also been identified on the planet Mars. In fact, hematite deposits on Mars played a significant role in suggesting the past presence of water on the planet. The hematite found on Mars is thought to have formed in ancient aqueous environments, indicating the possibility of past liquid water on the planet’s surface.

It’s worth noting that hematite can occur in various forms and appearances, such as botryoidal (globular), tabular, massive, or as micaceous flakes. These different forms contribute to the diverse range of hematite occurrences in nature.

Due to its abundance and wide distribution, hematite serves as an important source of iron ore for the iron and steel industry. It is mined in many countries, including Australia, Brazil, China, India, Russia, and the United States, among others.

Geological Formation of Hematite

Hematite can form through several geological processes depending on the specific environment and conditions. Here are some of the main geological formations associated with hematite:

1. Banded Iron Formations (BIFs): One of the significant sources of hematite is banded iron formations. BIFs were formed during the Precambrian era, between 3.8 billion and 1.7 billion years ago. These formations consist of alternating bands of iron-rich minerals, including hematite, and chert or silica-rich layers. BIFs formed in ancient oceans as a result of the precipitation of iron and silica from seawater, often associated with the activity of iron-oxidizing bacteria. Over time, these layers were compacted and lithified into sedimentary rock.
2. Hydrothermal Processes: Hematite can also be formed through hydrothermal processes, where hot, mineral-rich fluids circulate through fractures or faults in rocks. These fluids often carry dissolved iron and other elements. When the fluids cool and react with the surrounding rocks, hematite can precipitate out and form veins or replacement deposits. Hydrothermal hematite is commonly associated with other minerals such as quartz, calcite, and sulfides.
3. Weathering and Oxidation: Hematite can form as a result of weathering and oxidation of iron-bearing minerals in rocks. When iron minerals are exposed to oxygen and water over long periods, they undergo chemical reactions that lead to the conversion of iron into hematite. This process is especially prominent in environments with abundant oxygen and moisture, such as tropical or humid climates. The weathering of iron-rich rocks, such as basalt or magnetite-bearing rocks, can result in the formation of hematite-rich soils and residual deposits.
4. Metamorphic Processes: Hematite can also form during metamorphism, the process by which rocks undergo changes in temperature and pressure. Under specific conditions, such as in contact metamorphism near igneous intrusions, iron-bearing minerals can react and transform into hematite. This metamorphic hematite is often found in veins or nodules associated with altered rocks.

It’s important to note that hematite can form in various geological environments, and the specific formation mechanisms can vary depending on the local conditions. The presence of hematite can provide valuable insights into the geological history and processes that have occurred in a particular area.

Associated minerals and rock formations

Hematite is often associated with certain minerals and rock formations. Its occurrence alongside these minerals can provide valuable clues about the geological processes and conditions in a particular area. Here are some of the common minerals and rock formations associated with hematite:

1. Quartz: Quartz is frequently found alongside hematite. These two minerals often form in hydrothermal veins and can occur together as vein fillings or as intergrown crystals. The combination of hematite and quartz is aesthetically pleasing and is sought after by collectors.
2. Magnetite: Magnetite (Fe3O4), another iron oxide mineral, is often associated with hematite. Both minerals are commonly found in banded iron formations (BIFs) and can occur together as alternating layers within the rock. Magnetite is also known to alter and oxidize into hematite through weathering processes.
3. Limonite: Limonite is a mixture of various iron oxides, including hematite, goethite, and other hydrated minerals. It often occurs as an amorphous or earthy brown material associated with weathered iron-rich rocks and soils. Hematite and limonite can be intermixed or transition into one another.
4. Chert: Chert, a type of microcrystalline silica (SiO2), is commonly associated with hematite in banded iron formations. BIFs consist of alternating layers of hematite and chert, resulting from the precipitation of iron and silica-rich minerals in ancient marine environments.
5. Siderite: Siderite (FeCO3) is an iron carbonate mineral that can occur alongside hematite. It is often found in sedimentary iron ore deposits, where it forms as a result of chemical reactions between iron-rich fluids and carbonate minerals. Siderite can be found intermixed with hematite or as separate layers within a rock formation.
6. Goethite: Goethite (FeO(OH)) is another common iron oxide mineral often associated with hematite. It is frequently found in soils, weathered rocks, and mineral deposits. Goethite and hematite can occur together, forming mixed iron oxide minerals or as distinct phases within a geological formation.
7. Banded Iron Formations (BIFs): Banded iron formations, as mentioned earlier, are important rock formations associated with hematite. These formations consist of alternating bands of iron-rich minerals, such as hematite and magnetite, and silica-rich layers. BIFs are a significant source of iron ore and provide insights into the geological history of the Earth.

These associated minerals and rock formations provide important context and understanding of the geological processes and environments in which hematite is formed. They also play a role in the economic significance of hematite as an iron ore and influence the overall appearance and composition of hematite-rich deposits.

Industrial Uses of Hematite

Hematite is an important mineral in various industrial applications, primarily due to its high iron content. Here are some of the main industrial uses of hematite:

1. Iron Ore: Hematite is one of the primary sources of iron ore. It is mined extensively for its iron content, which is extracted and processed to produce iron and steel. Iron and steel are vital materials used in construction, manufacturing, transportation, and many other industries.
2. Steel Production: Hematite is a key ingredient in the production of steel. It is used as a primary iron ore feedstock for blast furnaces. The iron extracted from hematite is combined with other materials, such as coke (carbon) and limestone, in the blast furnace to produce molten iron. This molten iron is then converted into steel through various refining processes.
3. Pigment and Paint Industry: Hematite is also used as a pigment in the paint and pigment industry. Its distinctive reddish-brown to black color, as well as its ability to provide opacity and durability, make it suitable for producing red and brown pigments. Hematite pigments are used in various applications, including paints, coatings, inks, plastics, and ceramics.
4. Jewelry and Ornamental Use: Hematite has been used for centuries in jewelry and ornamental objects. Its metallic luster and dark color make it a popular choice for beads, pendants, and other jewelry components. Hematite jewelry is known for its earthy appeal and is often worn for its grounding and balancing properties.
5. Magnetic Applications: Certain forms of hematite exhibit weak magnetic properties, making them suitable for magnetic applications. Magnetic hematite, also known as hematine or “magnetic stones,” is often used to create magnetic jewelry, such as bracelets and necklaces. While the magnetic properties of hematite are relatively weak, they still find use in certain therapeutic and magnet-related products.
6. Abrasives and Polishing Compounds: Hematite is used as an abrasive material in various applications. Finely ground hematite powder is used as an abrasive in polishing compounds, metal finishing, and surface preparation. It can be used for polishing metals, glass, ceramics, and gemstones.
7. Water Treatment: Hematite has been used in water treatment processes, particularly for the removal of contaminants like arsenic and heavy metals. Its high surface area and reactivity make it effective in adsorbing and removing impurities from water.

These are just some of the many industrial uses of hematite. Its abundance, high iron content, and distinctive properties make it a valuable mineral for a wide range of applications in sectors such as metallurgy, construction, manufacturing, and materials science.

Distribution

Hematite is widely distributed around the world and can be found in various countries and geological formations. Here are some notable regions and countries known for their hematite deposits:

1. Australia: Australia is one of the world’s leading producers of hematite. Major hematite deposits are found in Western Australia, particularly in the Pilbara region. The Pilbara is known for its extensive iron ore mines, including those in the Hamersley Range, Mount Tom Price, and Paraburdoo.
2. Brazil: Brazil is another significant producer of hematite, particularly in the state of Minas Gerais. The Iron Quadrangle region in Minas Gerais is renowned for its vast hematite deposits, along with other iron ore minerals. The Carajás Mine, located in the state of Pará, is one of the largest hematite mines in the world.
3. China: China is a major producer and consumer of hematite. The country has extensive hematite deposits, primarily found in the provinces of Liaoning, Hebei, Shanxi, and Anhui. The massive hematite deposits in China contribute significantly to the country’s iron and steel industry.
4. India: India is one of the largest producers of hematite and iron ore in the world. The state of Odisha, particularly the Keonjhar and Sundargarh districts, is known for its rich hematite deposits. Other states like Jharkhand, Chhattisgarh, and Karnataka also have significant hematite resources.
5. Russia: Russia has substantial hematite deposits, with major occurrences in the Kursk Magnetic Anomaly in the Kursk and Belgorod regions. These deposits are part of the extensive iron ore resources in the region and play a crucial role in Russia’s iron and steel production.
6. United States: In the United States, hematite deposits can be found in various regions. The Lake Superior region, including Minnesota, Michigan, and Wisconsin, is known for its hematite-rich Mesabi Range, which has been a significant source of iron ore for the U.S. steel industry. Other states, such as New York, Arkansas, and Missouri, also have hematite occurrences.
7. South Africa: South Africa is home to significant hematite deposits, particularly in the Northern Cape province. The Sishen Mine, located in the Kathu area, is one of the largest open-pit hematite mines in the world.

Apart from these countries, hematite is also found in many other regions globally, including Canada, Sweden, Ukraine, Venezuela, Iran, and Kazakhstan, among others. The mineral’s widespread distribution reflects its abundance and importance as an iron ore resource in various parts of the world.

Hematite gemstone

Hematite is sometimes used as a gemstone due to its metallic luster and striking appearance. However, it’s important to note that hematite is not a traditional gemstone like diamonds or rubies. Instead, it is classified as an iron oxide mineral with gemstone-like qualities.

Hematite gemstones are typically polished into cabochons or beads for use in jewelry. Here are some key points about hematite as a gemstone:

1. Appearance: Hematite has a distinctive metallic gray to silver-black color. Its surface can exhibit a high metallic luster, often resembling polished metal. The gemstone may also display a reddish-brown color when polished, known as “red hematite.”
2. Polishing and Cutting: Hematite is usually shaped into smooth, rounded cabochons, which showcase its lustrous surface. It can also be faceted, although this is less common. Hematite beads are popular for use in bracelets, necklaces, and earrings.
3. Size and Shape: Hematite gemstones can vary in size and shape, depending on the desired use and jewelry design. Cabochons can range from small to large, while beads come in various sizes and shapes like spheres, ovals, and rondelles.
4. Jewelry Use: Hematite gemstones are commonly used in jewelry for their unique appearance. They can be set in rings, pendants, earrings, and bracelets, either as standalone pieces or combined with other gemstones or metals for contrast and visual appeal.
5. Metaphysical and Spiritual Properties: Hematite is associated with grounding, protection, and balancing energies in metaphysical beliefs. It is believed to enhance focus, boost self-confidence, and provide a sense of stability. Some individuals wear hematite jewelry for its supposed energetic and healing properties.
6. Care and Maintenance: Hematite gemstones are relatively durable, but they can be susceptible to scratches and damage from rough handling or harsh chemicals. It is advisable to avoid exposing hematite jewelry to harsh cleaning agents and acidic substances. To clean hematite gemstones, use a soft cloth or mild soapy water, and gently dry them afterward.

It’s important to purchase hematite gemstones from reputable sources to ensure their authenticity and quality. While hematite may not have the same rarity or value as traditional gemstones, its unique appearance and metaphysical associations make it an appealing choice for jewelry enthusiasts.

References

• Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
• Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
• Mindat.org. (2019). Hematite: Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].