The Vein Structures of the Gogô-Myaku (No.5 Vein) and the Occurrence of Iron Sulphide Minerals at the Konomai Mine, Hokkaido

Abstract

Gogo-Myaku (No.5 Vein) is one of the representative veins in the Konomai Mine in the Kitami District, Hokkaido, the most famous gold-silver mine in Japan.
In this paper, the writer gives a preliminary account of the characteristic features and genesis of the vein. The vein is an epithermal gold-silver quartz vein type in which the mineralization may be divided into the following stages:
Facies 1 (F₁) Quartz-calcite-adularia, and pyrite facies. (early stage).
Facies 2 (F₂) Quartz-adularia, Au-Ag minerals, and pyrite facies. (middle stage).
Facies 3 (F₃) Quartz-clay, minerals, Au-Ag minerals, and pyrite-marcasite facies. (late stage).
Facies 4 (₄) Quartz-calcite, pyrite-marcasite facies. (last stage).
It is remarkable that marcasite is abundantly formed in F₃ facies. Pyrite and marcasite are not usually associated with Au and Ag minerals.