SECONDARY QUARTZITEB AND THE FORMATION OF KAOLIN, PYBOPHYLLITE AND ALUNITE DEPOSITS OF TAN MAI KEG-ION, VIET NAM

摘要

One of the most remarkable achievements in research and finding of non-metallic mineral deposits of Vietnam is the discovery of kaolin, pyrophyllite and alu-nite deposits in Tan Mai region,NE Viet nam. The Tan Mai region is a part of the Mesozoic An Chau Depression in the southern margin of the South China ancient platform. Rhyolite-granite dffu-slves ard intrusives are widespread. Related metasomatic-hydrothermal secondary quarzites generated from primary rhyolite-dacite tuffs occur in the form of big lenses distributed along NE-SW faults. Industrial deposits of kaolin, pyrophyllite, alunite and interesting gold and sliver mineralizations are just found in these secondary quartzite formations. In the Tan Mai deposit typi cal zonal structures of ore bodies are determined with following mineralogical associations: quartz-sericite, quartz-pyrophyllite-diaspore, quartz-kaolinite -dickite, quartz-alunite, tnicrocrystal-line quartz.The results of mineralogical study and technological application in the production of ceramics, refractories, aluminum alums, plastic art rock carvings etc... have shown that these secondary quartzite deposits will certainly play a practical role in the development of the Vietnamese industry.