Cu3(As,Sb)S4 minerals from the Baia Mare metallogenic district, Eastern Carpathians, Romania – a case study from the Cisma ore deposit

Abstract

The occurrence of Cu₃(As,Sb)S₄ minerals, i.e. the enargite and luzonite-famatinite series, is poorly known in the Neogene Baia Mare metallogenic district, NW Romania, with few records and no analytical data. This study provides the first EPMA and XRD data on enargite/luzonite from the Baia Mare metallogenic district, i.e. the Cisma ore deposit from the Băiuţ metallogenic field, and the Herja ore deposit. Vein-type ore bodies bearing Cu₃(As,Sb)S₄ minerals from Cisma are hosted by Paleocene–Eocene flysch successions, while the host rock of the enargite-bearing ore from Herja is unknown. The enargite and luzonite-famatinite series are known as “exotic” in low sulphidation epithermal ore deposits, “typical” in high sulphidation epithermal deposits in association with tennantite, and “sometimes common” in small amounts in intermediate sulphidation epithermal ore deposits. The occurrence of enargite/luzonite in the Baia Mare district suggests the need to update the metallogenic interpretation for several ore deposits, partly at the district scale in relation to other ore deposit/mineralogy features, e.g. vuggy silica, hypogene argillic alteration.