Geology and Ore Deposits of the Omidani Mine, Especially On the Fusei Deposit
1969 Volume 19 Issue 94-95 Pages 133-146
Details
1969 Volume 19 Issue 94-95 Pages 133-146
The Omidani Mine is located at about 4km southwest of the Akenobe Mine. The geology of the area consists mainly of Palaeozoic formations (Maizuru group), with several intrusives of the Cretaceous to earlier Tertiary age.
The ore deposits are composed of many gold-bearing silver quartz veins, all of which occur mostly in slate and sandstone alternations of the maizuru group.
The Fusei deposit, which has been extensively developed in the mine, has the vein pattern of an acute intersection by two directions of WNW and NW, dipping 60°to 80° north or south. There are many bonanzas along andesite dikes. Each unit vein has width of 40-150 cm, strike length of 30-200 m, and plunge length of 60-300m.
Principal ore minerals are argentite and native silver. The average grade of ores, which recently has been produced, is 1.5-2g/t Au and 450-480g/t Ag.
Geophysical prospecting (resistivity method) has been successful in locating the Au-Ag-quartz veins in slaty rock.
