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Gray, red, black, altered white/tan, flow-banded pumice dacite
in Lassen Volcanic National Park
larger version, 1200px
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
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