Rhyolite

Rhyolite is an igneous, volcanic rock, o felsic (silica-rich) composeetion (teepically > 69% SiO₂—see the TAS classification). It mey hae ony texture frae glassy tae aphanitic tae porphyritic. The mineral assemblage is uisually quartz, alkali feldspar an plagioclase (in a ratio > 1:2—see the QAPF diagram). Biotite an hornblende are common accessory minerals.