Wall-Rock alteration of biotite hornfels at the Tyrnyauz deposit, Russia

Abstract

A new zonation type of W–Mo-bearing altered biotite hornfels at the Tyrnyauz deposit is reported. The review of zonation indicates a subsequent transition into the mobile state of CaO, MgO, FeO, and Al₂O₃ and retention of volume owing to dissolution or deposition of quartz as an excess mobile mineral. The main features of zonation are similar to those in acid leaching columns; the input of strong CaO base into the outer zone is unusual.