Rhodochrosite(redirected from dichroite)
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(also manganese spar), a mineral of the carbonate class with the chemical composition MnCO3. It contains 61.71 percent MnO and 38.29 percent CO2, as well as admixtures of Fe, Mg, Zn, and sometimes Co. Rhodochrosite crystallizes in the trigonal system to form massive granular aggregates or incrustations. Crystals (usually rhombohedral) are rare. Rhodochrosite is pink, red, or greenish gray with a vitreous luster. It has a hardness of 3.5–4 on Mohs’ scale and a density of 3,600–3,700 kg/m3.
Rhodochrosite often occurs in hydrothermal sulfide veins and metasomatic deposits in association with, for example, rhodonite, manganese garnet, and hausmannite. Sedimentary rhodochrosite deposits are of commercial importance. The largest rhodochrosite deposits are located in the USSR, in the Northern Urals, and in the USA, in Butte, Mont. Rhodochrosite is used as a raw material in the smelting of ferromanganese and as an additional charge in the smelting of cast iron and steel; it is also used in the chemical industry.