熊本県折立鉱山産ウエリン石

概要

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Welinite has found, as the fourth occurrences in Japan, from the Oritake bedded manganese ore deposit in Kumamoto Prefecture, which is embedded in the low grade metamorphic chert in the Southern Chichibu belt. Welinite occurs in rhodochrosite-manganoan clinochlore veins cutting Chocorate ore composed of hausmannite, tephroite and rhodochrosite, and as fine grain up to 10μm in diameter. It is yellowish brown to brown in color under the micro-scope. Chemical analysis by EDS gave SiO_2 13.48-16.02,FeO 1.11-2.90,MnO 56.74-58.18,MgO 0.63-1.10,WO_3 16.66-22.32,Na_2O 0.16-0.53wt%. There is slightly posibility of the substitution of W for Si. Welinite seems to have occurs as alteration products of tephroite and was formed by an interaction between tephrite and WO_3 bearing hydrothermal solution as follows : equations (1) and (2). (1) 4MnMn_6SiO_<12>→10Mn_2O_3+4Mn_2SiO_4+O_2(2) 3Mn_2SiO_4+WO_3+H_2O→Mn_6WSi_2O_<12>(OH)2+SiO_2
愛媛大学の論文
2000-03-17