Grain Size and Texture of Silver Minerals from Duk-Eum Ore Deposits

덕음광산(德音鑛山) 은광물(銀鑛物)의 입도(粒度)와 조직(組織)

The Duk-Eum mine located in Kongsan-myeon, Naju-gun, Cheolanamdo is producing silver ore mainly, with rare gold association. The grade-up and recovery of the concentrates have been concerned to the main problem. And then, this study aimed at applying the basic data for ore processing. In the first half of the study, the attempts were made to identify the ore minerals, this followed by determination of the mineral texture, paragenesis, grain size, and size distribution by employing the microscopical method and the etching test. The results of the study are as follows: 1. The ore deposit is composed of the hydrothermal fissure linked veins, and filling cavities are mostly tensile fractures or joints, in rhyolitic rocks as a wall rock. 2. The principle ore minerals are native silver, acanthite, canfieldite, pyrargyrite, galena, tetrahedrite, sphalerite, pyrrhotite, chalcopyrite, chalcocite, covellite, zincite, and the gangue minerals are quartz and calcite. 3. The grain size of each ore minerals before grinding are; max. $2\frac{1}{2}$ mesh, medium 48-100 mesh(main size, contained over 80%), min. 3200mesh. And the grain size of each ore minerals after grinding is; max. 42mesh, medium 65-250mesh(main size, contained over 80%), min. 3200mesh. 4. The properties of the mineral texture effected on the ore dressing are follows; a) Inclusion texture; the fine grains of chalcopyrite is included in most acanthite, and rarely, that of galena included in acanthite. b) Exsolution texture; pyrargyrite is exsolved in acanthite. c) Replacement texture; native silver replaced pyrargyrite, and acanthite replaced galena. d) Interlocking paragenetic texture; the interlocking paragenetic minerals are pyrite, chalcopyrite, chalcocite, canfieldite. e) Fissure filling texture; chalcopyrite was filled along the cracks in acanthite. Among of the above texture, it is impossible to liberate the grains of a), and more difficult to liberate those of b) and c), while easy to liberate those of d) and e).