Abstract
Clay minerals of epithermal deposits occur in two different environments.(1) Regional alteration zone in the mineralizing hydrothermal system.(2) Veins and wall rock alteration zone. Regional alteration zone is subdivided into the high temperature “propylitic zone” (deep propylitic zone and shallow propylitic zone) and low temperature “smectite-zeolite zone”. Veins and wall rock alteration zone are characterized by diminution or vanishment of albite or plagioclase and are classified into central “silicif ied zone”, deep “sericite-chlorite zone”, shallow “kaolinite-sericite zone” and outer “argillic zone”.
