silicic

{{Short description|Adjective to describe magma or igneous rock rich in silica}}

File:Streckeisen for intrusive quartz igneous rocks.svg for classification of plutonic rocks, silicic rocks are uncoloured at the top of the figure (Q is for Quartz which is pure silica)]]

Silicic is an adjective to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent.{{cite web|url=http://volcanoes.usgs.gov/vsc/glossary/silicic.html |title=USGS Volcano Hazards Program Glossary - Silicic |publisher=USGS |date=2013-09-19 |accessdate=2016-01-02}} Granite and rhyolite are the most common silicic rocks.

Silicic is the group of silicate magmas which will eventually crystallise a relatively small proportion of ferromagnesian silicates, such as amphibole, pyroxene, and biotite. The main constituents of a silicic rock will be minerals rich in silica-minerals, like silicic feldspar or even free silica as quartz. These are just part of all the other silicate minerals that make up 90% of the earth's crust.

This broad classification is refined in practice based on more detained compositional studies where ever possible in the science of mineralology.