Purdilla Gypsum Project (SA)
Located south of Streaky Bay on western Eyre Peninsula are coastal salinas Lake Purdilla and Lake Toorna which contain abundant gypsum (CaSO4) which could potentially be used within plaster board. Gypsum occurs as both coarsely crystalline selenite (grains >2 mm), sand-sized gypsarenite and finer gypsite, which form by inflow of groundwater and seawater during winter and subsequent evaporation and precipitation of salt and gypsum during summer.
The distribution and thickness for the gypsum varies throughout the lake system with the thickest accumulation being 5 m. Historical investigations and drilling conducted pre-1985 estimated a total gypsum resource of 58 Mt with an average thickness of ~2.1 m and grade of 87.5% gypsum, though more drilling and analyses are required to define a new resource consistent with the JORC code and modern resource reporting requirements. However, the historical data clearly indicate that Lake Purdilla potentially contains the largest undeveloped gypsum resource in Australia.
Figure: Lake Purdilla showing distribution of high-grade gypsum intersections from historical drill holes
Project details last updated January 2012