The mineralogy of propylites of the large Peschanka porphyry copper deposit (West Chukotka)

The Au-Mo-Cu porphyry Peschanka deposit is confined to the Egdygkych Pluton (K₁). The deposit comprises three major types of metasomatic rocks: quartz-K-feldspar-biotite, propylites and quartz-sericite. In their chemical compositions, amphiboles of propylites range from early magnesiohornblende to tremolite-actinolite. Compared to magmatic K-feldspar, the metasomatic K-feldspar is enriched in barium (up to 7.3 wt % BaO). Tourmaline belongs to the intermediate member of the oxydravite-povondraite series. The Al content in chlorite decreases to the outer zones of propylitization, which is caused by a decrease in the temperature of mineralization.