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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

RHODOCHROSITE


RHODOCHROSITE (Rhodochrosit—Rhodochrosite—–одохрозит) (Bergmann, 1782 in Hausmann, J.F.L. 1813), from Gk. “rhodon” – a rose and “chroma – a coloring, referring to its color.

Composition & Properties. Carbonate – Mn[CO3], trigonal system. Hardness 3.5-4. Density 3.5-3.8. Glass luster to pearl one. Perfect cleavage in three directions. Fragile. Rhodochrosite is rarely found as idiomorphic crystals up to 20 cm. in size, but usually – as massive grained aggregates, not rarely with light colored stripes. Its massive parallel-fibrous varieties are known, sometimes in the shape of stalactites and kidney-shaped aggregates like glass head. Transparent or translucent. Color: light rose, raspberry-red, orange-brownish, and with admixtures and veins of manganese oxides – brownish-black. A rare ornamental variety is greenish rhodochrosite, resembling malachite. Rhodochrosite is often found in mixture with rhodonite and tephroite – trade name viellaurite. A sphaerolitic variety with the admixture of zinc is called zincrhodochrosite, with the admixture of iron – ponite, with the admixture of zinc and iron – capillitita; with the admixture of calcium – calciodiadochit, with the admixture of cobalt – cobaltorhodochrosite, with admixture of quartzmanganese chert, manganquartz or horn-mangan; and with significant admixture of calcite and rhodonitecalcite-rhodochrosite or calciodialogite.

Deposits. It is formed at contact-metasomatic deposits, in hydrothermal veins and sedimentary layers. In Russia, in the Polar Urals, at the Poachvozh manganese deposit, they registered significant quantities of fine-grained and kidney-shaped aggregates of rhodochrosite together with manganocalcite, tephroite and rhodonite. In the North Urals, rhodochrosite was found in concretions of sedimentary manganese ore of the Polunochnoye deposit. In the South Urals, at the deposits Kyzyl Tash and South Faizulinskoye, in the region of Magnitogorsk, rhodochrosite is found together with rhodonite in skarns and in rocks of jasper formation. In Buryatia Rep., at the Dzhida tungsten deposit, in hydrothermal veins, they found crystals of rhodochrosite up to 10 cm. long. In the same association it was found in the Primorskiy Region, at the Tigrinoye deposit, 150 km. east from Dalnerechensk. In the Khabarovsk Region, we should mention a finding of rhodochrosite at the Khakanja deposit. On the Chukchi Penin., in the Pyrkakaiskiy mine and tin ore area, to the southeast from Pevek, they discovered rhodonite-quartz-rhodochrosite rocks with insets of native gold, which were of interest as an ornamental stone.

In the Ukraine, rhodochrosite is found in manganese ore of the Nikopol’skoye deposit, Zaporozhye. In Zakarpats’ka Region its concretions up to 30 cm. are found in the Chivchinskye Mts., in siliceous-carbonate manganese ore. In Crimea, at the Kerchenskoye iron ore deposit, rose rhodochrosite is incrusted in the surface of shells and sometimes completely fills them. In Georgia, concretions of rhodochrosite are found at the Chiatury deposit of the sea-sedimentary origin. In Central Kazakhstan, at the Karaoba deposit, there were findings of well-formed crystals of rhodochrosite up to 12 cm. in size. Besides, in the Atasuiskiy Dist. rhodochrosite is found at the deposits Eastern Kounrad, Ushkatyn III and at the Alexandrovskiy mine. In Europe, deposits of ornamental rhodochrosite were mined in Romania: at Rosia Montane (form. Verespatak), at Baia de Arie¸ s (form. Offenbanya), Alba Dept., and at Baia-Sprie (form. Felsobanya), Maramureš, Dept. At the deposits Cavnic (form. Kapnik) and Sàcârambu (form. Nagiag), Hunedoara Dept., they found transparent crystals available for faceting and collection druses of rhodochrosite and sphaerolites of raspberry spar. In Bulgaria, crystals of rhodochrosite at the Madan ore field, and at Davidkovo locality are found. In Slovakia, crystals of rhodochrosite in ore veins of the Banská Štiavnica (form. Schemnitz) deposit was discovered. In Germany, findings of rhodochrosite at the Louise mine, Hornhausen, Sachsen-Anhalt, are known; also at the Wolf mine, near Herdorf, and at Waldalgesheim, Rhineland-Palatinate. In France, in the Haut Pyrenees at La Cabesses deposit, rhodochrosite is found in mixture with rhodonite. The local name of this variety is lacroisit, or torrensite. In Scotland, concretions of rhodochrosite in modern sea sediments of the Loch Fine Gulf are found.

In South Africa, in the Northern Cape Prov., at the sedimentary Wessels manganese deposit, they extract gem-quality rhodochrosite. They found its dark red crystals up to 5 cm. in size there. At the discovered in 1975 N’Chwaning deposit they extract crystals of rhodochrosite up to 7 cm. and their radial-rayed clusters and sphaerolites up to 10 cm. in diameter. Faceted stones up to 60 ct. are made from them. In Australia rhodochrosite in crystals and in grained stripped aggregates extracted as additional material at the lead-zinc Broken Hill deposit. In Japan, on the Hokkaidö Is., at the mines Inakuraisi and Oe, they found well-formed crystals of rhodochrosite, and in the Aomori Pref., at the Oppu mine, they found kidney-shaped forms and stalagmites of rhodochrosite of ornamental quality up to 12 cm. in cross-section.

In the Argentina, there are the biggest deposits of ornamental rhodochrosite. One of them is in the San Luis Prov., another one – in the Catamarca Prov. – the Capillitas mine, near Andalgalá. The last one was opened in 1885 at the silver mine of Incas forgotten since the 13th cent. Rhodochrosite has been extracted there since 1930. It is represented there with stalactites up to 5 m long and 30 cm. in cross-section. Bandy and festooned structures in basal slabs are typical for it. The local name for such slabs is Inca rose, besides, crystals available for faceting are found there. Among other deposits of this territory, we should mention those in the north of Mexico, in the Chihuahua State, at: the mines El Potosí and Santa Eulalia, near Aquiles Serdán, with sphaerolites of rhodochrosite up to 4 cm. in diameter and transparent crystals up to 2 cm. long. At the Cananea deposit, in the Sonora State, transparent crystals of rhodochrosite reached 5 cm. long. In Peru, transparent crystals of rose and red rhodochrosite up to 20 cm. at the Pasto Bueno deposit, Ankash Dept., and at the Huallapon mine, were found. In the U.S.A., in Colorado, gem-quality crystals of rhodochrosite up to 16 cm. were found at the Sweet Home mine, Park Co. There also a giant rhombohedral crystal of rhodochrosite “Alma King” was found, which was exhibited at the jewelry and gemstones show in Tucson (1993). From transparent crystals of this deposit they manufactured faceted stones up to 61 ct. In Montana, similar crystals were found at the Butte deposit, in Utah – at the Park City deposit. In Canada, crystals of rhodochrosite up to 11 cm., red rosettes to 20 cm. at the Mont St Hilaire, Québec, were found.

Synonyms. Capillitita, after the Capillitas deposit in the Argentina | Dialogite, from Gk. “dialoge” – doubt, because of its non-definite content | Manganese cobalt ore | Manganese red ore | Manganspath, Germ. | Ponite, after the chemist P. Poni | Rosinca, stalactites of deposits San Luis Prov., Argentina | ~ spar: manganese ~, zinc-manganese ~, raspberry ~, red ~, rose ~, Germ., obs. | Inca stone | Strömit, obs.

Treatment. Rhodochrosite was not well-known at the gemstone market till 1950. Its massive variety is used mainly for manufacturing of beads, cabochons, caskets, and carved work of art. Transparent crystals of rhodochrosite are faceted, mainly for collection purposes. Faceted stones are usually up to 20 ct. The biggest faceted stone from rough material from South Africa was 59.75 ct.

Similarity. Rhodochrosite looks like rhodonite, dolomite and rose quartz.

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