Studies on compositional variations and geneses of raremetal bearing minerals

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The total number of works carried out during the three years as the period of this project exceeds 10, they being publications and oral presentations. The following three points outline the reached conclusions.1) The mineral groups including rare-metal bearing minerals subjected to the researches on their compositional variations and geneses are oxides, arsenates, and silicates from manganese ore deposits, oxides of rare earth elements from pegmatites, sulpharsenides of Ni and Co in sedimentary rocks, sulphides of Ag, Pb, Bi, Te, Sb, Mo, Sn, V and As in hydrothermal veins, phosphates including Sr, Ce, and Nd in hydrothermally altered rocks. The papers and oral presentations dealing with these minerals are for their compositional variations and geneses.2) The chemical analyzes employing the energy dispersive X-ray spectrometer have now enabled to cover those of nearly all elements reaching 66 in total, and have been carried out on more than 50 species of element, sulphide, oxide, and silicate minerals. The analyzed materials can be standards for the chemical analyzes of these elements, enabling to meet the requests of researchers out of our office.3) In relation to heavy minerals in psammitic rocks and sands, their time and space distributions, influence of contact metamorphism and that of regional metamorphism were investigated. More than 10,000 points of garnets and spinels were analyzed, proving that the analyzes can provide important informations on the origina thereof. The distribution of rare-metal bearing minerals is very sensibly variable due to influence of not only intense metamorphism but also very faint one.