• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.265-277
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• 2015

Hydrothermal alteration patterns and environment are studied by mineral assemblages and chemical analyses of surface and core samples from Miryang pyrophyllite deposit. The alteration zones of this deposit can be divided into three zones on the basis of mineral assemblage; advanced argillic, phyllic, and propylitic zone. Advanced argillic zone mainly consists of pyrophyllite-dickite (-quartz) and corresponds to principal mining ore. The common mineral assemblage of phyllic zone and propylitic zone are sericite-quartz-dickite and chlorite-quartz, respectively. Horizontal and vertical alteration patterns and major element geochemistry indicate that pyrophyllite ores have been formed several times by hydrothermal alteration. And it also suggests that the huge ore bodies may be extended from the deeper part of recent quarries to the south-southeastern direction. The paragenesis of ore minerals and polytype (2M) suggest that ore deposit was formed at about $300-350^{\circ}C$.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.93-101
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• 1992

Several "Napseok" mines are distribute in the Miryang area where the volcanic rocks are hydrothermally altered. The "Napseok" are pyrophyllite and dickite, with a small amount of silicates such as quartz, illite, tosudite and dumortierite. Other associated minerals are oxides, hydroxides, sulfides, sulfates and phosphates. Pyrophyllite which occurs as 2M polytype exhibits that the basal spacing increases due to dehydroxylation at 750${\circ}C$. Halloysite shows tubular forms. Wavellite is precipitated in fissures during the latest stage of the hydrothermal alteration process. Five mineral zones, that is pyrophyllite-deckite, illite, halloysite, silica, and albite-chlorite zones, are recognized with decreasing alteration degree. Clay minerals were formed by leaching of Si and alkali ions fron the country rocks, considering mineral assemblages, pyrophyllite polytype and thermodynamical data reported in the literature, temperatures of formation of main clay deposits are assumed to be 270 to 350${\circ}C$.