Eagleton Rhyolite

3D Model

This rhyolite specimen is an ignimbrite that is part of the Carboniferous (Visean) series of volcanics of the Tamworth Belt of the Southern New England Orogen (Australia). More specifically it is part of the Eagleton Volcanics, which in turn are part of the Gilmore Group. Eagleton is ~10 kilometres north of Raymond Terrace. The specimen exhibits fractured quartz and k-felspar phenocrysts set in an ash groundmass. The large patches of orange in the groundmass are ash components that have been affected by alteration the has produced very fine-grained clinoptillite (a member of the zeolite family). The unusual mauve colouration of most of the groundmass is also likely caused by a secondary zeolite. The specimen is ~18 centimetres long (longest axis).