Andesite

Andesite is a black to gray rock with between 53 and 63 weight percent silica (SiO₂). Common minerals in andesite include plagioclase feldspar, pyroxene, and iron oxide. Andesites are very common on stratovolcanoes, where they form both thick lava flows and moderate-sized explosive eruptions of tephra. Andesites are erupted at temperatures between 900 and 1100° Centigrade.

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