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Phonolite is an igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. Mineral assembly is usually abundant feldspatoids and alkali feldspar, and lesser plagioclase. Biotite, amphiboles and pyroxene are common accessory minerals. Quartz is absent.

Some phonolite outcrops make a musical sound when struck -- hence the name.

See also: igneous rocks, list of rocks