南部石と杉石 : 日本で新鉱物として発見され, その後宝石質の結晶がみつかった珍しい鉱物2種 [in Japanese] Nambulite and Sugilite : Two New Minerals Found in Japan and Later Found as Gem Materials [in Japanese]
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Nambulite, LiNaMn_8Si_<10>O_<28>(OH)_2, and sugilite, (K, Na) C(H_2O), Na]_2 (Fe^<3+>, Na, Ti, Fe^<2+>)_2 (Li, Al, Fe^<3+>)_3 Si_<12>O_<30>, are two new minerals found and described for the first time in Japan. At the time of findings of the two minerals, no body imagined that these could be gem materials. But, recently, two minerals of gem quality have been found in Africa. Nambulite found at Kombat, Tsumeb, Nambia is deep red in colour and transparent, attaining 3cm in length, and cuttable as facet stones. Sugilite found in Wessels mine, Karahali manganese field, Cape Province, South Africa is violet in colour, and translucent, beautiful enough for cabochon cutting. This was at first reported as sogdianite, but later was identified as sugilite. Both are most unusual cases for new minerals found in Japan, and thus are introduced in this paper.
- Journal of The Gemmological Society of Japan
Journal of The Gemmological Society of Japan 9(2-3), 55-60, 1982
The Gemmological Society of Japan