CONDITIONS OF THE FORMATION OF RICH SILVE R-ARSENIC ORES AT AKTEPE DEPOSIT (CENTRAL TIEN-SHAN)

There have been found about 60 ore minerals at Aktepe deposit; one thi rd of which are Ag-bearing ones (Ag-Sb-Hg, Ag-Cu-Sb-As-S, Ag-Pb-Bi-S s ystems). The formation of silver productive assemblages was connected with arsenic mineralization deposition within the main ore stage. Nati ve silver and Ag-Sb, Ag-Cu solid solutions were deposited at first, fo llowed by sulphosalts of Bi, As, Sb and Ag-sulphides. Formation of sil ver-arsenic mineralization occured at 280-100-degrees-C and pressure b elow 100 bar from the solution of elevated salinity (13-19 wt.% equiv. NaCl). Dissolved aerated cool waters being involved in the system sti mulated the deposition of native silver followed by Eh increase and ac anthite and other silver sulphide and sulphosalt deposition. Spatial c ombination of assemblages including native silver with silver sulphide and sulphosalt mineralization resulted in formation of bonanza ores w ith extremely high silver content.