A final stage of gypsum exploration in the Lake Malata area, 70 km north-west of Port Lincoln, was carried out under mineral claims and retention leases which were cancelled in 1991. Drilling of 62 auger holes (total 258 m) proved a resource of 1.2 Mt of gypsite and gypsarenite with an average grade (%) of 92.3 CaSO4.2H2O, 3.40 CaCO3, 1.94 NaCl, and 2.95 acid insolubles, a primary composition deemed as suitable for the intended market of plaster manufacture only after beneficiation prior to calcination, including fine grinding to remove clay. Diamond drilling (5 holes, total 87 m) disclosed a further inferred resource in excess of 30 Mt of 80-90% gypsum beneath the salt crust of the lake.