東星鑛山의 地質과 鑛床, 試錐結果를 中心하여

On the geology, ore deposit and drilling summary of Dongsung copper mine

The mine of our present concern is situated at Shim-ri, Gusan-myon, Changwon-gun, Kyongsang-namdo, with lattitude 128˚35 ~36 N and longitude 35˚03 ~04 E. This mine has not been noticed until the intermittent geological survey for the ore deposits were initiated from September, 1967 till 1970. The main mineralized zones, No. 1 and No. 2 zones, were studied by the diamond drilling of 9 holes down to the total depth of 1,140m, and found to have ore reserves of Cu 1.9996 ore, estimated to reach around 358,000M/T (proved 117,000 M/T, indicated 241,000 M/T, which triggered the new exploitation of this mine. Geological composition of the district near the mine is mainly from the andesite belonging to the Silla Series of Kyongsang System and the distribution is broadly spread. Ore deposits are the hydrothermal one, filling the shear zone formed alongside the andesite main joint. There are two stripes of copper bearing mineralized zone which are about 40~70 meters apart and parallel to each other, in addition to which two others are expected. The strike of the main mineralized zone lies at N15˚~20˚W, the dip at 60˚~70˚NE. The principal components of the ore mineral are chalcopyrite, bornite and as secondary, cuprite, tenorite, azurite and malachite. Pyrite, magnetite, specular hematite, very little of galena, sphalerite, quartz, epidote, zoisite, chlorite and calcite are found as gangue mineral. Confirmed by the drilling, the main mineralized zone, No. 1 zone, has the length of 320m, average width of 1.62m, Ag 26g/t, Cu 1.8496 and the average width of the ore zone except the narrow barren andesite horse interposed in the mineralized zone is 1.32m with Ag 32g/t and Cu 2.26%. The mineralized zone No.2 is 340m long, 1.00m wide with Ag 30g/t and Cu 2.15%. Neglecting the barren andesite horse the width is 0.73m with Ag 42g/t and Cu 2.94%.