داسیت

Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz.

Key facts

Rock.name: Dacite
Rock.type: Igneous
Rock.image: Black porphyritic dacite (upper Holocene, 14 May 1915; Devastated Area, Lassen Volcano National Park, California, USA) 51.jpg
Rock.caption: Dacite from the Lassen Volcano National Park
Rock.composition: Plagioclase feldspar, quartz
Rock.composition_secondary: Hornblende, biotite, and pyroxene
Rock.class: Felsic
Rock.texture: Aphanitic or porphyritic
Rock.Equivalent: Intrusive variant is granodiorite