| Abstract |
Several rare minerals of vanadium silicate were found in the manganese ore from the Yamato mine, Amami-Oshima Island, the largest of the southern islands of Kagoshima Prefecture. They have been determ...ined as yamatoite (manganoan vanadium garnet), haradaite (strontian vanadium silicate), and manganoan roscoelite. Also ardennite, a sort of vanadian epidote, is seen, but not yet determined. Reports on yamatoite and haradaite are now in preparation. So this paper deals mainly with their paragenesis and some details on roscoelite. The roscoelite from the Yamato mine is the first occurence of this mineral in Japan. It is found as veinlets cutting the rhodonite ore or the silicified wall rock, sometimes also disseminated. Associating minerals are yamatoite, haradaite, barite, rhodonite, rhodochrosite, albite, and quartz. Dark green roscoelite flakes show distinct pleochroism under the microscope, from pale greenish yellow to dark bluish or brownish green. Refractive indices, β≒γ= 1. 669, and nearly uniaxial. Optical character negative. Roscoelite was examined spectrochemically with the results that V, Mn, Si, AL Fe, and K were contained as main constituents. X-ray powder data show that the type of polymorphism of this mineral is 2M_1 not in accord with the previous data (lM type for roscoelite). So this mineral may be called 2-layer manganoan roscoelite.show more
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