dacite

/ dā′sīt′ /

1. A fine-grained light gray volcanic rock consisting primarily of quartz, plagioclase feldspar, and potassium feldspar, and also containing biotite, hornblende, or pyroxene. It is the fine-grained equivalent of granodiorite.

Example Sentences

Eichelberger, J. C. Origin of andesite and dacite: evidence of mixing at Glass Mountain in California and at other circum-Pacific volcanoes.

From Nature

Chunks of juvenile gray dacite fell like hail, some as large as golf balls.

From Scientific American

Those gasses ripped and plucked existing rock from the debris avalanche and the ground, mixed that rock with the hot young dacite from the cryptodome, and hurled the whole mass along at incredible speeds.

From Scientific American

I went to school at the foot of a mountain made of dacite, the same kind of magma that blew Mount St. Helens apart.

From Scientific American

As hikers start toward the “Old Way,” a gully that leads up to the crater, volcanic rocks called dacites and andesites dot the landscape.

From New York Times