Rhodochrosite


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rhodochrosite

[‚rōd·ə′krō‚sīt]
(mineralogy)
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.

Rhodochrosite

 

(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 ?
During the 2015 Tucson gem shows, gem dealer Mark Kaufman (Kaufman Enterprises, San Diego, California, USA) had some rough and cut transparent rhodochrosite from another locality: Brazil.
Visitors to the exhibition were greeted, just inside the entrance, by four aesthetic cabinet specimens in individual glass cases: a rhodochrosite from the Sweet Home mine, Colorado; a green fluorite from Riemvasmaak, South Africa; a native gold from the Eagle's Nest mine, California; and an amethyst crystal group from the Anahi mine, Bolivia.
He conducted specimen mining operations at a number of localities throughout the west, including Colorado for rhodochrosite, Idaho for barite, and his home state of Nevada for a variety of minerals.
First, Ramos and Burillo had splendid specimens of rhodochrosite taken a year or so ago from the Manuelita mine, Yauli Province, Lima Department.
Manganese occurs primarily as rhodochrosite (MnCO3) and pyrolusite (MnO2) and can be readily upgraded to electrolytic manganese dioxide (EMD) which currently sells for US$2,000 per tonne in the North American market.
In the text Wiedenbeck lingers on some of these excitements, and offers personal angles on them: for one, there's a good account of the Sweet Home Rhodochrosite fever that came to town in 1993, and later, echoing it, comes the story of Wiedenbeck's at last buying, from Bryan Lees in 2002, the (barely affordable) Sweet Home rhodochrosite specimen of his dreams.
The Wyndham pit yielded manganese oxide minerals, including well-crystallized specimens of twinned black hausmannite crystals and also some attractive specimens of pink rhodochrosite (collected by Sir Arthur Russell in the 1930s).
These veins locally contain significant concentrations of rhodochrosite and are associated with minor concentrations of pyrite, sphalerite, and galena mineralization both within the veins and in the adjacent host rocks.
He contributed two articles to the Mineralogical Record: one on rhodochrosite in 1971 and the other (with Richard Kosnar) on the minerals of the Colorado mineral belt in 1976.
Present feed for the four-man mining operation at the site is coming from a recently discovered chalcedonic quartz and rhodochrosite vein exposed in a shallow pit.
But I still would have preferred to see a larger proportion of higher quality specimens: these books are, after all, addressed to the collector, and if we collectors are to be reminded that there is more to the world of beautiful minerals than gold, proustite, azurite, rhodochrosite and tourmaline, we need to see some specimens of rock-forming minerals performing at their peaks.
Rhodochrosite with Fluorite Strawberry Pocket, Sweet Home Mine, Alam, Colorado ex-collection Gene Meieran