Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

The geology of the studied area consists of andesite, andesitic pyroclastic rocks, rhyolite, rhyolitic pyroclastic rocks, fine-grained biotite granite, diorite dyke and alluvium. Rhyolitic pyroclastic rocks were hydrothermally altered by acid sulfate solution, resulting in the formation of silicified and pyrophyllitic alteration zones. The most abundant minerals are pyrophyllite, kaolinite and quartz, and minor minerals are alunite, illite, diaspore, corundum and pyrite. Alunites are associated with pyrophyllite, kaolinite, quartz and/or pyrite. It indicates that amount of H2SO4 may be attained to produce acid sulfate alteration in this area. Gold contents with major and trace elements have been determined for a total of eighty-four samples of rocks and minerals from this study area by inductively coupled argon plasma (ICAP) and neutron activation analyzer (NAA). Detectable amount of gold (>2 ppb) was found in twenty-one samples of eighty-four samples analyzed. Gold content was the highest up to 46 ppb for the altered rhyolitic pyroclasitic rocks collected near fracture. More than 5 ppb Au, which is higher than average Au content of earth crust (4 ppb), was deteced only in the samples of andesitic and rhyolitic pyroclastic rocks. However, gold contents of alteration minerals such as pyrophyllite, diaspore, and corundum were less than 4 ppb. Average gold contents are increasing in the order of rhyolitic pyroclastic rocks, andesitic pyroclastic rocks and altered minerals. Generally, gold content tends to show positive correlations with contents of Mg, Eu, Fe, Sb and U.