Silica Beach, 45 km SSE of Streaky Bay, is the source of a well sorted and well rounded, very coarse-grained sand, extracted in limited quantities since 1970 for filtration and other uses at Whyalla Steelworks. Sand and gravel are derived locally from erosion of fresh and kaolinized granite, and from Tertiary gravel. These are reworked, sorted and deposited onto Silica Beach by wave action in an essentially closed system. Other deposits of very coarse sand were examined at nearby Tyringa Beach and at Point Labatt. Local conditions at Silica Beach were found to favour the accumulation of a substantially larger deposit with more uniform distribution of the very coarse sand fraction.