Chromite
Chromite (Iron Chromium Oxide)
General
Category	Mineral
Chemical formula	iron magnesium chromium oxide:(Fe,Mg)Cr2O4
Identification
Color	Black to brownish black
Crystal habit	Octahedral rare; massive to granular
Crystal system	Isometric; hexoctahedral
Cleavage	absent
Fracture	Conchoidal
Mohs Scale hardness	5.5
Luster	Submetallic
Refractive index	Subtranslucent to opaque
Pleochroism	N/A
Streak	Dark brown
Specific gravity	4.5 - 4.8
Fusibility	Infusable
Solubility	?
Other Characteristics	Weakly magnetic
Major varieties
Magnesiochromite

Chromite, iron magnesium chromium oxide: (Fe,Mg)Cr₂O₄, is an oxide mineral belonging to the spinel group. Magnesium is always present in variable amounts, also aluminium and iron substitute for chromium. Chromite (Iron Chromium Oxide) Source: US Government File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Chromite (Iron Chromium Oxide) Source: US Government File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Minerals are natural compounds formed through geological processes. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Atomic mass 51. ... An oxide is a chemical compound of oxygen with other chemical elements. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In crystallography, the cubic crystal system (or isometric crystal system) is the most symmetric of the 7 crystal systems. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... A fracture is the separation of a body into two, or more, pieces under the action of stress. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... The refractive index (or index of refraction) of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a vacuum. ... Pleochroism is an optical phenomenon where due to double refraction of light by a colored gem or crystal, the light is divided into two paths which are polarized at a 90° angle to each other. ... Minerals are natural compounds formed through geological processes. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Fusibility is the ease with which a material will melt. ... It has been suggested that Solid solubility be merged into this article or section. ... An oxide is a chemical compound of oxygen with other chemical elements. ... Minerals are natural compounds formed through geological processes. ... The spinels are any of a class of minerals which crystallize in the isometric system with an octahedral habit. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ...

Chromite is found in peridotite and other layered ultramafic intrusive rocks and also found in metamorphic rocks such as serpentinites. Ore deposits of chromite form as early magmatic differentiates. It is commonly associated with olivine, magnetite, serpentine, and corundum. The vast Bushveld igneous complex of South Africa is a large layered mafic to ultramafic igneous body with some layers consisting of 90% chromite making the rare rock type, chromitite. Chromite is the chief ore of chromium. Peridotite Peridotite is a dense, coarse-grained rock, consisting mostly of the minerals olivine and pyroxene. ... Ultramafic (or ultrabasic) rocks are igneous rocks with very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content). ... Iron ore (Banded iron formation) Manganese ore Lead ore Gold ore An ore is a volume of rock containing components or minerals in a mode of occurrence which renders it valuable for mining. ... Olivine The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)2SiO4 in which the ratio of magnesium and iron varies between the two endmembers of the series: forsterite (Mg-rich) and fayalite (Fe-rich). ... // Headline text Magnetite is a ferrimagnetic mineral form of iron(II,III) oxide, with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. ... Serpentine Serpentine is a group of common rock-forming hydrous magnesium iron phyllosilicate ((Mg, Fe)3Si2O5(OH)4) minerals; it is also often rich in other metal ores, including chromium, manganese, cobalt and nickel. ... Corundum is the crystalline form of aluminium oxide and one of the rock-forming minerals. ... The Bushveld igneous complex contains one of the richest ore deposits on Earth. ... In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ... Ultramafic (or ultrabasic) rocks are igneous rocks with very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content). ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Atomic mass 51. ...

Chromite is also used as a refractory material. The term refractory can refer to multiple things: A refractory clergyman is one who refused to swear an oath to the French Revolution-era French state under the Civil Constitution of the Clergy. ...

The only ore of chromium is the mineral chromite. In the western hemisphere, chromite ore is produced only in Brazil and Cuba; By comparison, about 80% of world production of chromite comes from India, Iran, Pakistan, Oman, Zimbabwe, Turkey and Southern Africa. Southern Africa itself produces about half of this.

In Pakistan Chromite has been mined in the Zhob District of Baluchistan since 1902. Currently the major mining company in Pakistan is Pakistan Chrome Mines Ltd. Chromite is found in the ultramfic rocks in the Zhob District of Baluchistan, Most of the Chromite is of metalurgical grade with Cr₂O₃ averaging 46% and a chrome to iron ratio of 3:1. Pakistan Chrome Mines Ltd. ... Baluchistan (or Balochistan), also known as Greater Baluchistan is an arid region of south Asia, presently split between Iran, Pakistan and Afghanistan. ...

References and external links

• Dana's Manual of Mineralogy ISBN 0-471-03288-3
• Guilbert, John M., and Park, Charles F., Jr. (1986) The Geology of Ore Deposits, Freeman, ISBN 0-7167-1456-6
• Mineral Galleries: Chromite
• Webmineral.com
• Minerals.net

http://minerals.usgs.gov/minerals/pubs/country/1998/9324098.pdf