A small area which was centred on the eastern end of Kangaroo Island, ~10 km south-east of Penneshaw, has been explored for exploitable quantities of lithium or tantalum-bearing minerals, specifically spodumene, zinnwaldite and lepidolite, because...
A small area which was centred on the eastern end of Kangaroo Island, ~10 km south-east of Penneshaw, has been explored for exploitable quantities of lithium or tantalum-bearing minerals, specifically spodumene, zinnwaldite and lepidolite, because some such minerals, e.g. elbaite gem tourmaline and lepidolite mica, are know to occur near there in pegmatite bodies formed on the margin of a large Delamerian, high crustal level emplaced S-type fractionated granite pluton. The area had not previously been tested for its lithium and associated minerals potential, despite the local presence of the aforesaid pegmatitic minerals plus minor known tin mineralisation. The subject ground was taken up because the licensee had earlier discovered a pervasive pegmatites dyke system, striking in a south-westerly direction, which extends from its adjoining EL 6212 to the east. At the outset of exploration, all available records of the local basement geology and past exploration history were consulted to obtain any useful rock geochemical data and geophysical information that might guide locating shallowly buried pegmatite dikes, since the majority of the licence area apart from creek lines is soil covered. When field work commenced in March 2019, the open farmland was systematically walked by Rob Cameron, a consultant geologist who has lithium search experience, to identify places having poorly exposed pegmatite and pegmatite float from subcrop. Numerous previously unrecorded pegmatite and aplite dykes were encountered, and some undocumented (on SARIG) small shallow workings were found. A conversation made with a local elderly farmer revealed that these workings are those of the Black Spider tin mine. The only historical reference to this mine was later found via a literature search done on TROVE, it coming from the Adelaide Advertiser newspaper issue of Wednesday, 31/10/1894. First-pass grab rock chip geochemical sampling of the pegmatites, aplites and float (21 samples) to send for laboratory multi-element XRF analysis and peroxide fusion ICP tests returned generally poor lithium and related element assay values, the highest being 60 ppm Li, 136 ppm Cs and 613 ppm Rb, all in sample KID078. The abandoned Black Spider tin mine workings returned poor lithium and tin values, however, the pegmatite exposures sampled in the mine area are very weathered. The host pegmatite there extends to the west under shallow cover, and could warrant more investigation. Because of the lack of encouraging indicators of the minerals sought, no more work was done on EL 6213, and at the end of two years a decision was reached to fully surrender its tenure.
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