Prospecting at the Omine Mine, Iwate Prefecture
1965 Volume 15 Issue 73 Pages 227-233
Details
1965 Volume 15 Issue 73 Pages 227-233
The Omine mine is located at about 20 km east of Tono City, Iwate Prefecture. At about 1 km northeast of this mine is found the Omine iron ore deposit of the Kamaishi mine. The geology of the Omine mine area is composed of Permian clay slate. sandstone and hornfels, intruded by granodiorite and quartz diorite. Occurrence of limestone, though not distributed on the ground surface, has been confirmed underground (at a horizon of 295m above sea level) by boring. The deposit is a copper ore deposit of a contact-metasomatic high temperature hydrothermal origin, occurring in the hornfels. The copper ore occurs as irregular masses or pipes, presenting a network or impregnation pattern. Chalco pyrite is the leading ore mineral, accompanied by a large amount of, cubanite. The ore deposit comprises five ore bodies, No. 1 (D1) to No.5 (D5), and three of them, No. 1 (D1), No. 2 (D2) and No.3 (D3), are being worked.
Since the mine was reopened in 1952, the mine area has been explored by various methods, as summarized below. a. First period (1952-1959) Improved with the working on the remaining ore of D1, the skarn zone was traced by boring and level-driving, and D2 and D3 were detected. b. Second period (1960-1961) Detailed geologic survey was made for D1 and D2. The ground surface was also surveyed in detail. Preparation for regional Prospecting of the skarn zone was made. c. Third period (1961-1962) The northern area was explored by level-driving. Scale of distribution of the skarn zone was investigated. d. Fourth period (end of 1962-1964) Detailed investigation of the detected skarn zonee was made. Ore body D4 was discovered. e. Fifth period (1964-present) Detailed investigation of D4 is in progress.
The policy of the present prospecting aims chiefly at (1) tracing of the stage of ore deposit formation and the skarn zone, and (2) confirmation of the limestone boundary. In order to gain satisfactory results efforts will be made also in clarifying the relationship between the ore deposit and the igneous rocks and the zone of fissures.
