Table of Contents
Hematite is dense and hard, it is the most important ore of iron because of its high iron content and its abundance. The mineral occurs in various habits: steel-gray crystals and coarse-grained varieties with a brilliant metallic luster are known as specular hematite; thin, scaly forms make up micaceous hematite; and crystals in petal-like arrangements are called iron roses. It also occurs as short, black, rhombohedral crystals and may have an iridescent tarnish. The soft, fine-grained, and earthy form of hematite is used as a pigment. Important hematite deposits occur in sedimentary beds or in metamorphosed sediments. A compact variety known as kidney ore has a kidney-shaped surface. A form of ground hematite called rouge is used to polish plate glass and jewelry.
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
Chemical Classification | Oxide minerals |
Chemical Composition | Fe2O3 |
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
Hematite under the microscope of xpl Hematite under the microscope of ppl
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 |
Hematite Occurrence
Large hematite deposits appear in banded iron formation. The thist mineral is water soluble and may appear at the bottom of the water and may also appear in non-aqueous environments, which are related to volcanic events. Clay-sized hematite crystals may also appear as a secondary mineral shaped by soil erosion procedures and, together with other iron oxides or oxyhydroxides containing goethite, are responsible for the red color of the soils that have been weathered in many tropics, historic or other conditions.
Hematite Uses Area
- It is the main iron ore in the world.
- It is one of the most important pigment minerals.
- It is a very dense and inexpensive material that is effective in stopping
- X-rays and is therefore used for radiation protection around medical and scientific equipment.
- It is also useful as a ballast for ships.
- Polishing compounds,
- Minor gemstone
Distribution
Widespread. Exceptional crystals
- from Switzerland, as at Fibbia, St. Gotthard, Uri; Binntal, Valais; Cavradi, Tavetsch, Gra¨ubunden; and many other places.
- At Ocna de Fier (Mor´avicza; Vask˝o), Romania.
- From Rio Marina, Elba, Italy. At Cleator Moor, Cumbria, England.
- From Kragerøand Hiassen, Norway.
- In Brazil, large crystals from Mesa Redonda and Congonhas do Campo, Minas Gerais; at Itabira and in the Brumado mine, Bahia; at Miguel Burnier, Ouro Prˆeto.
- From the Kuruman district, Cape Province, South Africa.
- At Nador, Algeria.
- In the USA, in the Thomas Range, Juab Co., Utah, and near Quartzsite, La Paz Co., Arizona.
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].