Hydrothermal alteration mineralogical studies of Sangestan formation in Ali Abad ?e? Dareh Zereshk ?e? Yazd

Abstract:
      Sangestan's arkosic sandstones formation which are located in Central Iran zone, are locally affected by leucogranited plutons, which are caused by the late phase of Shir- Kuh has been altrated and made a collection of minerals consist of kaolinite- alonite and sericite. Alonite is formed in random disseminate veins.
   This index mineral, considerable for precious metals deposit. Alonite forms in gossans zone at high oxygen fugacity and while occur oxidation of sulphides. Then these solutions affected on pottasic arkosic feldspars and make the formation of alunite