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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

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ROMANECHITE


ROMANÉCHITE (Romanèchit—Romanèchite—–оманешит) (Lacroix, A. 1900), after its discovery location in Romanèche (now Romanèche-Thorins), 20 km west from Villefranche, Saône-et-Loire Dept., Bourgogne, France. Earlier, the general name for manganese oxides was psilomelane. It was discredited by the Commission of IMA. Oxide – (Ba,H2O)2Mn5O10, monoclinic system. Hardness 5-6. density 4-4.7. Half-metal luster, dull one in aggregates. Fragile. Romanèchite is widespread. Non-transparent, black. An ornamental variety of romanéchite is black glass head. Manganese oxides in the form of films and dendrites are found in rhodonite, opal, moss agate and landscape agate, enriching the ornamentally of these gemstones. Romanèchite is formed at sedimentary deposits, in the oxidation zone and in the weathering zone of manganese ores, in hydrothermal veins.

Synonyms. Barytpsilomelan | Black hematite | Black malachite | Black manganese | Psilomelane (psilomelanite), from Gk. “psilos: – smooth and “melanos” – black, after its appearance; syn. manganomelan | Brown stone | Agate tree | Stone tree | Wad | Black wad.

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