Study of Sulphur Ores (No.1)

(Bi-Sb Mineral from the Horobetsu Mine)

Abstract

The writer studied a Bi-Sb mineral from the Horobetsu mine (Hokkaido) megascopically, microscopically and by etching tests, micro-chemical tests, spot analyses and powder method of X-ray analysis. As a result of the study, the writer obtained the following facts:
1) This mineral has lead-white color and a needle-like crystal habit similar to boih bismu- thinite and stibnite.
2) This mineral occurs in small veinlets in the iron sulphide ore body of the Horobetsu deposit. 3) The optical properties are almost similar to those of bismuthinite and stibnite, but some of them seem to be of an intermediate character between these two minerals.
4) This mineral shows beautiful zonal structure after etching with KCN and KOH solution (Fig. 3). 5) By chemical analysis the writer decided that it had two components of Bi2S3 and Sb₂S₃, and that the value of Bi₂S₃ : Sb₂S₃ was almost 3 : 2 with some variation.
6) The results of spot analyses and powder method of X-ray analysis indicate that this mineral has no parallel intergrowth structure, and that it is a solid-solution of bismuthinite and stibnite.