Exploration for possible buried, stratiform, Palaeoproterozoic Willyama Group Ag-Pb-Zn ore deposits, over an area located 8-20 km north to north-northeast of Boolcoomata Homestead, comprised ground magnetic, Sirotem and IP surveys plus petrology,...
Exploration for possible buried, stratiform, Palaeoproterozoic Willyama Group Ag-Pb-Zn ore deposits, over an area located 8-20 km north to north-northeast of Boolcoomata Homestead, comprised ground magnetic, Sirotem and IP surveys plus petrology, surface mapping, and soil, rock chip and stream sediment sampling. RAB drilling (242 holes, total 10,101 m) into concealed bedrock returned anomalous Zn, Pb and Ag from within weathered and altered pelitic schists and minor epidote-rich calc-silicate rocks of the Bimba Suite over a 200 metre-wide mineralised zone at Ram Dam prospect, encountering values of up to 5000, 2700 and 5 ppm respectively over 3 m thick intersections. The ore minerals as seen under the microscope comprise pyrrhotite >> sphalerite > chalcopyrite > magnetite > pyrite >> galena, as irregular laminations and thin layers in the schists, generally making up less than 10% of any given sample. These sulphide minerals appear to become preferentially more concentrated adjacent to and within the calc-silicate interbeds. Two similar 500 metre-wide anomalous Pb-Zn zones were also identified at the Millierooka and McLennons North prospects. A 334 m deep diamond drillhole put down at Ram Dam in late 1990 recorded a 23.2 m thick interval in the Bimba Suite from 252.8 m depth grading at 0.36% Zn, 0.09% Pb, and 2.3 g/t Ag, including a 0.25 m thick section grading at 4.55%, 3.66%, and 65g/t respectively.
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