Chromium minerals

Chromite is a crystalline mineral composed primarily of iron(II) oxide and chromium(III) oxide compounds. It can be represented by the chemical formula of FeCr2O4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (MgCr2O4). Substitution of the element aluminium can also occur, leading to hercynite (FeAl2O4). Chromite today is mined particularly to make stainless steel through the production of ferrochrome (FeCr), which is an iron-chromium alloy.

thumb|Uvarovite - Saranowskiy Mine, Ural. Russia. Uvarovite is a chromium-bearing garnet group species with the formula: Ca3Cr2(SiO4)3. It was discovered in 1832 by Germain Henri Hess who named it after Count Sergei Uvarov (1765–1855), a Russian statesman and amateur mineral collector. It is classified in the ugrandite group alongside the other calcium-bearing garnets andradite and grossular.

thumb|Putnisite (animation) Putnisite is a mineral composed of strontium, calcium, chromium, sulfur, carbon, oxygen and hydrogen. It was discovered on the Polar Bear Peninsula in Shire of Dundas, Western Australia in 2007 during mining activity. Following identification and recognition by the IMA in 2012 the mineral was named after mineralogists Andrew and Christine Putnis. The formal description was published in 2014.

Bentorite is a mineral with the chemical formula . It is colored violet to light violet. Its crystals are hexagonal to dihexagonal dipyramidal. It is transparent and has vitreous luster. It has perfect cleavage. It is not radioactive. Bentorite is rated 2 on the Mohs scale.

Eskolaite is a rare chromium oxide mineral (chromium(III) oxide Cr2O3).

Stichtite is a mineral, a carbonate of chromium and magnesium; formula Mg6Cr2CO3(OH)16·4H2O. Its colour ranges from pink through lilac to a rich purple colour. It is formed as an alteration product of chromite-containing serpentine. It occurs in association with barbertonite (the hexagonal polymorph of Mg6Cr2CO3(OH)16·4H2O), chromite and antigorite.

Zincochromite is a zinc chromium oxide mineral with the formula ZnCr2O4. It is the zinc analogue of chromite, hence the name. It was first described in 1987 as an occurrence in a uranium deposit near Lake Onega, Russia. It has also been reported from Dolo Hill, New South Wales, Australia, and from the Tarkwa Mine in the Ashanti gold belt of Ghana.

Kalininite (ZnCr2S4) is a thiospinel mineral found in Russia in 1985 in the Pereval Marble Quarry, Slyudyanka (Sludyanka), Lake Baikal area, Irkutskaya Oblast', Prebaikalia (Pribaikal'e), Eastern-Siberian Region. It was named for P. V. Kalinin, Russian mineralogist and petrologist, investigator of the southern Baikal region.

Tongbaite is a rare mineral that has the chemical formula Cr3C2, or chromium carbide.

Wattersite is a rare mercury chromate mineral with the formula Hg+14Hg+2Cr+6O6. It occurs in association with native mercury and cinnabar in a hydrothermally altered serpentinite. It was first described from Clear Creek claim, San Benito County, California, USA in 1961. It was named to honor Californian mineral collector Lucius "Lu" Watters.

Loveringite is a rare metallic oxide mineral of the crichtonite group with the chemical formula . It is a late-stage magmatic mineral, formed in the residual melt of mafic layered intrusions in either the olivine-chromite, pyroxene, or plagioclase-rich layers.

Brezinaite, discovered in 1969, is a rare mineral composed of chromium and sulfur. It is found in meteorites, such as the Tucson Ring meteorite (Irwin-Ainsa meteorite), its type locality. It was also found in the New Baltimore meteorite and the Sikhote-Alin meteorite. Brezinaite was named in honour of Aristides Brezina (1848–1909), a past director of the Mineralogy-Petrology Section of the Natural History Museum, Vienna, Austria.

Knorringite is a mineral species belonging to the garnet group, and forms a series with the species pyrope. It was discovered in 1968 in the Kao kimberlite pipe in the Butha-Buthe District of Lesotho and is named after Oleg Von Knorring, a professor of mineralogy at the University of Leeds in England.

Guyanaite, CrO(OH), is a chromium oxide mineral that forms as an intergrowth with other chromium oxide minerals known as bracewellite (CrO(OH)) and grimaldiite (CrO(OH)) as well as eskolaite (Cr2O3) which in early findings were nearly indistinguishable from one another. These oxides formed so closely as intergrowths with one another that they were initially, and erroneously, identified as a single definite mineral previously known as merumite. Because of its complex history and the previously undiscovered nature of these chromium oxide polymorphs, the relevance of any information found in many

Carlosruizite is a sulfate or selenate–iodate mineral with chemical formula: K6(Na,K)4Na6Mg10(SeO4)12(IO3)12·12H2O. It has a low density (specific gravity of 3.36), colorless to pale yellow, transparent mineral which crystallizes in the trigonal crystal system. It forms a series with fuenzalidaite.

Joegoldsteinite is a rare sulfide mineral with the formula MnCr2S4. It was discovered in Social Circle meteorite found in Georgia, US. The mineral is named after Joseph (Joe) I. Goldstein.