Highlights
West Cobar Metals’ Managing Director, Matt Szwedzicki, commented: “The Bulla Park project is shaping up to have potential for a major copper – antimony – silver deposit. The antimony content is exceptional and with the global prices of antimony trading at nearly 2.5 times the price of copper, it is a good time to have drilled through a major intercept of antimony mineralisation.
We are now planning the next drill program to follow the deposit along strike.”
Mineralisation is dominantly tetrahedrite (copper – antimony sulphide) and minor chalcopyrite and stibnite (antimony sulphide). Antimony grades in all drill hole intercepts are approximately 30% to 35% of the copper grade, reflecting the theoretical composition of tetrahedrite (Cu12Sb4S13).
The mineralisation has developed over several stages. Syn-depositional siderite alteration of Lower Devonian (Winduck Group) silty fossiliferous sandstones is accompanied by chalcopyrite and tetrahedrite. Synsedimentary microfaults and dewatering structures are common indicating a tectonically active depositional and mineralising environment. When subsequently lithified, brittle faulting and fracturing has resulted in siderite-barite stockwork veining and hydrothermal breccias with tetrahedrite as the main copper-antimony mineral. Later faulting is associated with tectonic breccias, massive siderite-barite veins up to 20m thick and tetrahedrite and stibnite crystals filling vughs and veins (Figures 2 and 3).
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