島根県鹿足郡日原鉱山産Bi-Pb-Ag-S系鉱物の産状と化学組成

Occurrence and chemical composition of Ag-bearing mineral in the ores from the Nitihara mine，Kanoashi-gun，Shimane Prefecture，have been investigated．The ore deposits are veintype ones and intercalated in the slate．The samples collected from the dump are extremely silicified．The main ore minerals are pyrite，chalcopyrite，sphalerite and galena，and minor ones are pyrrhotite，bismuthinite，Bi-Pb-Ag-S mineral and covelline．Gangue minerals are quartz，chlorite and siderite．Veinlets of hematite，rutile and quartz are found in the gangue．
Bi-Pb-Ag-S mineral fills the interstices of quartz grains and the cavities in sphalerite．It shows elongated shape with 10-60μm long．This mineral is intruded and alternated by galena．Chemical compositions of the analyzed area，where the degree of alteration by the galena seems to be little，are Bi 46.6-48.8，Pd 26.3-28.3，Ag 7.4-7.6 and S 16.2-17 wt．％，which are very similar to those of vikingite．