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Nichromite (Ni,Co,Fe)(Cr,Fe,Al) 2 O 4 [1] is a black cubic metallic mineral and member of the spinel group. [5] Nichromite was originally reported from the Bon Accord nickel deposit in Barberton District, South Africa. [1]
Chromite contains Mg, ferrous iron [Fe(II)], Al and trace amounts of Ti. [5] Chromite can change into different minerals based on the amounts of each element in the mineral. Chromite is a part of the spinel group, which means that it is able to form a complete solid solution series with other members in the
Chromitite with bronzite phenocrysts from Stillwater Igneous Complex. Chromitite is an igneous cumulate rock composed mostly of the mineral chromite.It is found in layered intrusions such as the Bushveld Igneous Complex in South Africa, the Stillwater igneous complex in Montana and the Ring of Fire discovery in Ontario.
The mineral chromite is an iron chromium oxide with empirical formula FeCr 2 O 4. Structurally, it belongs to the spinel group. Magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (MgCr 2 O 4);. [1] Zincochromite is another example.
Download QR code; Print/export Download as PDF; Printable version; ... Iron(II) chromite is an inorganic compound with the chemical formula FeCr 2 O 4. Preparation
Crocoite is commonly found as large, well-developed prismatic adamantine crystals, although in many cases are poorly terminated. Crystals are of a bright hyacinth-red color, translucent, and have an adamantine to vitreous lustre.
The chromite ore is heated with a mixture of calcium carbonate and sodium carbonate in the presence of air. The chromium is oxidized to the hexavalent form, while the iron forms the stable Fe 2 O 3 . The subsequent leaching at higher elevated temperatures dissolves the chromates and leaves the insoluble iron oxide.
Predominance diagram for chromate. In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium.. 2 CrO 2− 4 + 2 H + ⇌ Cr 2 O 2− 7 + H 2 O. The predominance diagram shows that the position of the equilibrium depends on both pH and the analytical concentration of chromium.