Gypsum deposits occurring at Diamond Lake are at present being worked at the rate of 200 tons per week by Mr. C.D. Bartsch of Nuriootpa. The area of the deposits is private property owned by Mr. E.W. Wilson of Whitwarta, with minerals alienated from the Crown. Seed gypsum is transported by road to the South Australian Portland Cement Company’s works at Angaston, a distance of approximately 60 miles. Gypsum is used in the final stages of the manufacture of cement, its purpose being to slow down the setting rate of the product. During 1955 Mr. C.M. Willington (Mining Engineer) investigated the Diamond Lake deposits in connection with their possible use in the manufacture of plaster. A 10 ton sample of seed gypsum was taken from Section 19 by arrangement with the owner and tests were carried out at Pt. Pirie. A satisfactory plaster was made from the sample but the colour was off white, and the quantity available was estimated to be less than 4,000 tons. This quantity was insufficient to be of interest to plaster manufacturing organizations. The South Australian Portland Cement Company now require gypsum at the rate of 200 tons per week and supplies were initially obtained from deposits approximately 3 miles south east of Blanchetown. Following the closing of the Blanchetown punt during 1956 it was necessary to find other sources of gypsum and operations then commenced at Diamond Lake. Operations are continuing at this locality although the Blanchetown deposits are again accessible. Following an inspection in February 1957 by Mr. Willington, when the deposit was proving more extensive than when first examined it was suggested that a more detailed geological examination be made. The present examination was made during the period I6th-I8th July and entailed the drilling of 12 test holes, from which samples were collected for assay.