About the stone
Oamaru stone, sometimes called ‘whitestone’, comes from a 40m thick deposit of limestone 5km inland from the North Otago township of Oamaru. The distinctive creamy-coloured stone is bryozoan limestone, which is made up predominantly of calcium carbonate (90 per cent) with trace chemicals including alumina (1.5 per cent), iron oxide (0.5 per cent), and silica (0.5 per cent). The sedimentary rock is soft when first quarried but hardens on exposure to air. This, along with its uniform granular texture, makes it excellent for sculptural and ornamental purposes. As it is porous, it must be sealed if outside. “If it stays wet for a long time, the stone will go mushy and begin to break down,” says Shaugn. The stone has been quarried at various sites along the deposit since the 1860s, but Parkside Quarries at Weston, which opened in 1906, is the only remaining operation. It was originally sliced from the hillside using a steam-driven chainsaw mounted on rails but these days is cut with hydraulically operated 3m tungsten-tipped circular saws. The stone has been widely used as a building material in Oamaru, but also features on prominent buildings around the country, from Dunedin’s historic railway station to the Auckland Town Hall. Mount Somers limestone, found in mid Canterbury, is denser than Oamaru stone but its treatment is the same for carving. “You use the same tools but everything takes two or three times longer,” says Shaugn.