Silicic

Silicic is an adjective to describe magma or igneous rock rich in silica (SiO₂). The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent.¹ 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.

The "Shammar group" is a silicic and volcaniclastic sequence in northwestern Saudi Arabia.²