A kaolin deposit located 30 miles north-northwest of Port Lincoln is being appraised for its economic potential as a source of paper-coating clay. A geological consultant's investigations of newly acquired drillhole samples of the kaolin indicated that it was of a very high grade mineralogically, and suitable for use in the paper clay, filler clay and ceramic industries. Subsequent geological mapping of two areas having the apparently largest clay reserves showed that the development and preservation of kaolinization bears a close relation to basement rock type, and to folding and the degree of erosion, which partly resembles the present morphology. Substantial extensions to the clay lenses originally discovered at Vigar's Farm were found nearby to the north, south and east, allowing an estimated raw kaolin reserve of at least 30 million tons to be calculated. An exploration shaft was sunk to the groundwater table and a 50 ton bulk sample of clay extracted from within it for intensive pilot plant testing in Germany, particularly of the clay's rheological (viscosity) properties. To date the likely cause for the clay's poor viscosity has been shown to be a 4.5% Ca content in the kaolin composition, compared with approximately 0.2% Ca in other world standard kaolins.