EXTRACTION TECHNIQUES IN EXPLORATION EXTRACTION TECHNIQUES IN EXPLORATION FOR BURIED MINERALIZATION, CURARA WELL, WESTERN AUSTRALIA

At the Curara Well Au prospect, about 420 km NNE of Perth, WA, primary and lateritic gold mineralization are overlain by up to 20 m of barren transported overburden A previous study conducted for CRAE had suggested that mobile metal ion (MMI) extractions of soils located buried mineralization The site was therefore selected for a series of investigations of this and other partial and selective extractions in delineating buried mineralization Soil samples were collected from one profile and eight traverses in mineralized and background areas and were treated using various commercially available and in-house analytical extraction techniques The sequential selective extractions involved pH 5 acetate (for carbonate and adsorbed metals), followed by 0 11':1 hydroxylamine (Mn oxides) and 025 M hydroxylamine ('amorphous ' Fe oxides) As expected, most of the extractable Mn is dissolved with the 0 1 M hydroxylamine, with Co and (in part) Ba and Ni Extractable Mn correlates with extractable Fe, even though they are dissolved by different reagents, indicating an indirect secondary origin for these two phases (e g, surface drainage depositing Mn and Fe, or biological effects) Accordingly, other metals (REE, Cu, Pb and Zn) correlate with Mn, even though they are hosted by amorphous Fe oxides The partial extractions used were 4 M hydrochloric acid (HCI) (lSOC / 4 hours), mobile metal ion (MMI) extractions and Enzyme Leach There was good agreement between the combined results for the sequential selectiv