GOLD-COPPER-SULPHIDE MINERALIZATION OF QUARTZ-CARBONATE VEINS IN GABBRO-DOLERITES FROM THE CHEVZHAVARA DEPOSIT, SOUTH KARELIA
Gold-copper-sulphide mineralization in gabbro-dolerites (PR2ld) from the Chevzhavara building stone deposit is confined to quartz-carbonate veins cutting through a gently dipping sill. Mineralization displays several mineral types: magnetitic-pyritic (type 1 veins), pyritic-bornitic-chalcopyritic (type 2 veins), and hematitic-chalcosine (type 3 veins). Type 1 veins are large-crystalline epidote-calcitic. Skarnification evolves in the margins of larger sulphide-quartz-carbonate veins of type 2: grossular-andradite-series zonal garnets, calcite, epidote, and less often amphibole and chlorite are formed. Gold is present in cop-per-sulphide type 2 veins. Ore mineralization (in the productive stage of mineral formation) in the veins is represented by pyrite, chalcopyrite, bornite, Se-bornite, galena, claustha-lite, gold, and barite. Gold concentration in the veins varies within 0.06-31 g/t (8 samples). Type 3 veins contain hematite, chalcosine, chalcedony, and quartz; scattered, finely dispersed gold is occasionally encountered. Ore minerals are penetrated by chlorite and stilpnomelane. Macrocrystalline calcite and amphibole-asbestos veins are encoun- tered locally. Cu, Au, Co, Se, Zn, and Fe (in oxidized form) are the typomorphic elements of ore mineralization.