Deposit Synonyms

Elizabeth Creek; Mg 14; Mount Gunson

Mineral District

Mount Gunson Copper

Deposit Summary

Cu mineralisation at disconformity contact of dolomitic black shale of the Tapley Hill Formation & overlying Whyalla Sandstone. Indicated resource 1.1 Mt @ 1.7%Cu, 0.04%Co, & 17 g/tAg.

Deposit Description

MG14, black shale-hosted copper-cobalt-sulver sulfide mineralisation discovered at a depth of 25m in rotary drill hole MG14 in 1973 during pattern exploration drilling north of the sandstone-hosted Cattle Grid deposit. Mineralisation was controlled by the Marinoan disconformity at the base of the Whyalla Sandstone, where the principal host was a permafrost breccia horizon on the upper surface of the black dolomitic shales of the Tapley Hill Formation. Base metal sulphides formed through the replacement of diagenetic pyrite. Copper sulphide mineralisation comprises fine grained chalcocite, chalcopyrite, bornite, covellite, pyrite, carrolite, galena, sphalerite in gangue of dolomite, clay/sericite, quartz and siderite. The mineraisation formed a cement in more porous dolarenite clasts in the breccia and in dolarenite laminae in the underlying black shale. Gunson Resources Limited defined an indicated resource of 1.1Mt @ 1.7% Cu, 0.04% Co, and 17 g/t Ag in a flat-lying zone ~1.4km EW by 0.4km NS, thickness 3-8m, and 20-25m below surface beneath Whyalla Sandstone. The body dips gradually to the NW. Historically the inability to separate cobalt and silver from copper concentrates has impinged on the ability to realise any commercial value on the contained Co and Ag. Gunson Resources was pursuing avenues to fund research on processes to economically separate Co and Ag. The Cu-Co mineralisation is distributed a fine-grained, discrete and intergrown sulphides, with copper as complex, intergrown chalcocite, bornite, and chalcopyrite, and cobalt as carrollite in a gangue of dolomite, sericite, quartz, and siderite. Gindalbie Metals Ltd(now Coda Minerals Ltd) announced upgaded resource figure in January 2018 of 1.83Mtonne at 1.24%Cu, 334ppmCo, 14g/tAg at cutoff >0.5% Cu Eq.

Discovery Year

? 1973

Commodities

Copper, Cobalt, Silver, Lead, Zinc

Ore Minerals

Argentite, Bornite, Carrollite, Chalcocite, Chalcopyrite, Cobaltite, Covellite, Galena, Linnaeite, Sphalerite, Wittichite

Gangue Minerals

Clay mineral, Dolomite, Marcasite, Pyrite, Quartz, Sericite, Siderite

? Stuart Shelf

Pernatty Upwarp where Neoproterozoic strata thin out. Eroded wedge-out of the Tapley Hill Formation black shale. Mt Gunson deposits lie within corridor defined by this margin and wedge-out of Whyalla Sandstone. MG14 dyke and major fracture zone it occupies may provide conduit for mineralising fluids.