Kōrero: Rock, limestone and clay

This limestone quarry lies in the hills above Dunback, in North Otago. The hard, pure limestone (96–98% calcium carbonate) is processed into lime, which is used at nearby Macraes Flat gold mine for processing gold ore. When the cement works at Green Island near Dunedin was operating (1929–88), it used lime from this quarry. The limestone has also been used as a chicken-feed additive to maintain the quality of egg shells.