Image: Flow-banded rhyolite
Flow-banded rhyolite (15 cm x 11 cm), Pokolbin, Hunter Valley District, New South Wales.
- Stuart Humphreys
- © Australian Museum
Rhyolite is a silicic, acidic volcanic rock composed of quartz and alkali feldspar, with minor plagioclase and/or biotite. It is the volcanic equivalent of granite.