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Dacite


Gray, red, black, altered white/tan, flow-banded pumice dacite
in Lassen Volcanic National Park

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Dacite is an igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. Mineral assembly is usually quartz, alkali feldspar and plagioclase (in a ratio < 1:2). Quartz and alkali feldspars may be scarce. Biotite, hornblende and pyroxene are common accessory minerals.

See also: igneous rocks, list of rocks