Dacite
Volcanic rock intermediate in composition between andesite and rhyolite / From Wikipedia, the free encyclopedia
Dacite (/ˈdeɪsaɪt/) 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.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Mineraly.sk_-_dacit.jpg/320px-Mineraly.sk_-_dacit.jpg)
Dacite is relatively common, occurring in many tectonic settings. It is associated with andesite and rhyolite as part of the subalkaline tholeiitic and calc-alkaline magma series.