Since 1950, recorded production from ICI's Penrice marble deposit near Angaston has totalled 13,083,395 tonnes. High grade marble is used at the company's Osborne plant, while lower grade stone is sold for cement manufacture and roadstone, and small tonnages of the best quality material are used for whiting, foundry flux, glass and tile manufacture. The quarried steeply dipping marble bed forms part of a Lower Cambrian sedimentary sequence that also contains siltstone, schist, quartzite, calc-silicate and other marble horizons. The bed contains a high grade marble core flanked by narrow zones having a calcium carbonate content of less than 95%. A 6-hole diamond core drilling programme (total BQ core penetration 912.8 m) was recently conducted within the quarry for ICI by contractor the SA Department of Mines and Energy to define geological boundaries below the present workings, and to determine marble grades at depths significantly below those addressed in previous investigations. Existing geological plans have been updated to include the extent of current workings, and the plotted marble bed boundary has been modified. Currently measured reserves of marble total 12,400,000 tonnes, comprising 4,600,000 tonnes in the 4 and 5 Levels within the present quarry, plus 8,800,000 tonnes to down 3 Level in an area to the north. Large additional reserves could be obtained by widening the quarry, but this would necessitate mining substantial quantities of low grade marble and schist above the 3 Level. Significant reserves also exist to the south of the present quarry.