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MnCO3 A rose-red to pink or gray mineral form of manganese carbonate with hexagonal symmetry but occurring in massive or columnar form; isomorphous with calcite and siderite, has a hardness of 3.5-4 on Mohs scale, and a specific gravity of 3.7; a minor ore of manganese.



(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.

References in periodicals archive ?
Locally, it is a source of rhodocrosite. The known deposits at Capillitas consist of a series of massive sulphide veins which cut both the older granites and the Tertiary volcanics.
Although some of them certainly have reasonable specimens of sulfides, calcite, rhodocrosite etc.
Other "Romanian" specialties are man-made red potassium dichromate crystals on matrix (sold as realgar), calcite druses or concretions dyed pink to pass them off as specimens of rhodocrosite, and home-grown alum crystals.