Fundamental Studies of the Kuroko Deposits, with Special Reference to the Hanaoka Mine
(3) Preliminary Studies of the Ore of the Hanaoka Mine
1952 Volume 2 Issue 3 Pages 1-16
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1952 Volume 2 Issue 3 Pages 1-16
The writer reports here his studies of the fundamental characters of the three kinds of ore from the so-callad Kuroko deposits with special reference to the ores of the Hanaoka Mine. The effects of secondary sulphide enrichment are usually so strong on the deposits of this type, that black copper ores have been formed in many ore bodies of the Kuroko mines. These ores have been often called confusingly "proper. Kuroko ". For the present purpose these secondary apparent Kuroko ore are not treated in this paper.
At Hanaoka the Kuroko deposit consists of three kinds of ore, i. e., siliceous ore, yellow ore and black ore. It is very difficult to define the representative of them. From many chemical analyses of the ores, the writer calculated statistically the mean valne of the ratio of Cu, Pb and Zn of each kind of ore. The following are the results : siliceous ore… Cu : Pb : Zn=77 : 4 : 19, yellow ore… Cu : Pb : Zn=56 : 5 : 39, black ore… Cu : Pb : Zn=10 : 20 : 70.
The three kinds of ore in one ore body are found generally in the order of black ore, yellow ore and siliceous ore from the upper to the lower parts of the deposits. The grade of copper becomes gradually lower at the lower parts. This tendency of decrease of copper content, from upper to lower, is reverse to the change of the ratio of Cu : Pb : Zn. This presents a problem on the dressing of ore from the black ore deposit, from which it is said to be very difficult to get good recovery of copper at present.
The three kinds of ore were formed in order of siliceous ore, yellow ore, and, lastly, black ore. In other words the ore rich in chalcopyrite crystallized first, sphalerite-ores, next and ore rich in galena, last. Considering from data of chemical analyses of the various kinds of Kuroko ores., there seems to be some limit on the ratio of the constituent minerals such as chalcopyrite (Cu), sphalerite (Zn) and galena (Pb) in the Kuroko deposit.
