1966 年 82 巻 944 号 p. 983-988
The “Kurokô” or black ore named for its black colour is massive ore, composed of sphalerite, galena, chalcopyrite, tetrahedrite, pyrite, barite, gypsum etc. The “Kurokô” deposit occurs in Miocene formation rich in volcanic products mostly in Northeast Japan. Some of the “Kurokô” deposit are irregular massive shape, but others are lenticular and intercalated between the Miocene pyroclastics or sedimentaries. is noticed that many “Kurokô” deposits are accompanied by the dacitic dome in their underlying parts.
The genesis of the “Kurokô” deposit is a problem now in discussion among the Japanese geologists. is Interpreted in the three ways (i) hydrothermal replacement origin, (ii) submarine exhalative sedimentary origin, (iii) the combination of (i) and (ii).
The similar problem on the genesis of the strata-bound deposit is also a topic of the dispute among the geologists throughout the world.
Since 1955, many large ore bodies of the “Kurokô” deposit have been found in the northern part of Akita Pref., as shown in Table 1.
Now the large scaled prospecting project of the “Kurokô” deposit is being carried out in many promising places throughout Japan in co-operation with the private mining companies and Japanese goverment.