Auriferous limonitic stalactites from the Bimbimbie Gold Mine, New South Wales
The Bimbimbie gold mine is situated within a syntectonic granite mass that intrudes Ordovician metasediments 11 km south-west of Batemans Bay, NSW. Three gold-pyrite quartz veins occur within the mine area, the largest the Bimbimbie vein being the main producer. On the backs of a large stope into the Bimbimbie vein numerous limonitic (goethitic) stalactites occur. Two of these were assayed for gold giving 26.1ppm and 16.2ppm respectively. The chemistry of the process leading to the incorporation of gold in these stalactites is considered in terms of the solubility of gold in the thiosulphate ion.