釜石鉱山鉄・鉄銅鉱体における硫化鉱物の産状と分布
1978 年 28 巻 149 号 p. 203-213
詳細
1978 年 28 巻 149 号 p. 203-213
The ore deposits at the Kamaishi mine can be divided into iron, iron-copper and copper ore bodies. The authors studied the occurrence and distribution of sulfide minerals in the iron and iron-copper ore bodies, especially in the iron ore bodies located at the deeper parts of the Shinyama ore deposits (6D and EN-1 to 4), and in an iron-copper ore body called 7D. The results are summarized as follows:
1. In most of the studied iron and iron-copper ore bodies, there is no correlation between the Fe and Cu contents. There are two types of relations between the Cu and S contents. In one type, the S content varies with a constant, low content of Cu. In the other type, both the Cu and S contents change at variable ratios. The former is dominant in the iron ore bodies and the latter in the iron-copper ore bodies.
In the case of the copper ore bodies, the Cu content changes in direct proportion to the S content. From the ratio of Cu and S, the ratio of chalcopyrite to pyrrhotite, the dominant sulfide minerals in the copper ore bodies, are calculated to be 2:1.
2. Predominant iron sulfide minerals in the iron ore bodies are monoclinic pyrrhotite and pyrite, both of which appear to have been changed from hexagonal pyrrhotite. This observation, together with the fact that the copper content in the iron ore bodies is always low regardless of the sulfur content, suggests that the iron ore bodies were affected by low temperature hydrothermal solution carrying abundant sulfur but very little copper.
3. In general, the area of sulfide mineralization associated with magnetite mineralization coincides roughly with the area of iron ore bodies. Sulfide minerals are relatively abundant at the top and the bottom of the ore bodies, chalcopyrite being the dominant sulfide at the top and pyrrhotite at the bottom. The midde part of the ore bodies is poor in sulfides, forming high grade magnetite ore.
4. Sulfide minerals are concentrated mainly in the clinopyroxene skarn zone developed near limestone, and in the iron ore bodies. One of the most important factors for the deposition of Cu minerals is the distance from limestone.
