Native silver from Borovec (Štěpánov ore district)Article PDF
Native silver from Borovec (Štěpánov ore district)
Silver mining activities at Štěpánov ore district date back to 13th century. Besides the major ore minerals, the silver-bearing galenite with inclusions of freibergite, and the silver-bearing chalcopyrite, rare presence of native silver was encountered on dumps close to the shallow shaft Josef near Borovec (1 km N from Štěpánov). The mineralization occurs in quartz-carbonate veins cross-cutting marbles and metapelites. The native silver locally intergrows with native copper in quartz-calcite gangue or in quartz cavities; rarely, it is enclosed in cuprite or chrysocolla. Malachite and iron oxides and hydroxides are common constituents of the assemblage but in a small volume. Chemically, the native silver is very pure (~99 wt. % Ag) and except of low amounts of Cu (≤ 1 wt. %) it contains only traces of As (≤ 0.5 wt. %) Bi (≤ 0.13 wt. %).