Trade name for a type of rhyolite with a characteristic pattern.
Rhyolite, from Greek ῥεῖν rheĩn, to flow and λίθος líthos, stone, is a volcanic rock mainly consisting of quartz and feldspar.
Most rhyolites are of light colour, with a quartz content varying between 20 % and 60% and show porpyhyric structure, that is a fine grained matrix with embedded coarse crystals.
Old names for rhyolite were quartz porphyry and liparite, after the Lipari Islands (better known as Aeolian Islands) north of Sicily.