Mineral and chemical composition of the high-sulfidation epithermal Cu-V-Sn-As assemblage in the Assarel porphyry copper deposit, Central Srednogorie

Assarel porphyry copper deposit is located in the Panagyurishte ore district, Central Srednogorie, which is a part of the Late Cretaceous Apuseni–Banat–Timok–Srednogorie magmatic and metallogenic belt. This study reports a new data on the epithermal high-sulfidation ore mineralization described previously as “specific” and “rare”. The ore mineralization is associated with advanced argillic alteration and is represented by enargite, colusite, sulvanite, bornite. They occur as thin veinlets brecciating or crosscutting earlier small disseminated euhedral/subhedral to anhedral pyrite in quartz or subhedral/anhedral pyrite nest-like aggregates with zunyite, gypsum, rutile. Bornite is replaced by chalcocite and covellite, and enargite by covellite. Enargite contains Sn, Sb, Te, while colusite occurs as two distinct chemical varieties: 1) Sn-rich and Mo-bearing, with lower As content, and 2) Sn-poor, Ge-bearing, As-rich. Both varieties have 0.1–0.2 wt% Sb. Bornite and chalcocite contain small amounts of Se. Pyrite spatially associated with this mineralization is enriched in Cu, Co, and Ni, with Co/Ni and Co/As ≥ 2.