<報文>山形縣大張, 八久和兩鑛山附近の地質鑛床

概要

論文の詳細を見る
The gold copper bismuth deposits of Obari and Yakuwa Mines, Yamagata Prefecture, occur in muscovitized biotite hornblende granodiorite, granite and diorite porphyrite masses and covered with andesite and its tuff and agglomerate of probably upper middle miocene age. The deposits are believed to have been formed before the andestic igneous action. The ore deposits of this districts are developed along faults and joint planes in granitic rocks and may be divided into disseminated type and normal vein type. Ore minerals of the former type deposits are mainly of tetrahedrite, chalcopyrite, bornite, some Bi-Cu sulphide minerals and native gold, and gangues are muscovite, quartz and calcite. The latter type deposits may be classified by the mineral assemblages as follows : (1) bornite-chalcopyrite-molybdenite-pyrite-Bi-Cu sulphide mineral-quartz vein, (2) chalcopyrite-arsenopyrite-tetrahedrite-pyrite-quartz vein, (3) chalcopyrite-bornite-quartz vein, (4) sphalerite-galena-pyrite-quartz vein, (5) chalcopyrite-pyrite-quartz vein. Chalcopyrite often forms an oriented intergrowth with bornite, due to unmixing of their solid solution.
東北大学の論文
1953-03-25