Dacite

Description

This dacitic ignimbrite is from the old BMG quarry north of Raymond Terrace NSW. The Carboniferous rock is part of the volcanic arc that stretched from the Newcastle area to north Queensland and represents the western margin of the New England Orogen. The main minerals present are phenocrysts of hornblende, plagioclase and quartz, embedded in a welded glassy groundmass with a eutaxitix texture. There are also late veins of clinoptillite present. The quarry was a source of vast amounts of structural stone and aggregate used around the Newcastle area. It forms the main outer section of the Hunter breakwall and can be found in retaining walls around the city.