Rock Topics

Composition (Part 2)

Felsic Minerals

• Light-colored minerals such as muscovite mica, orthoclase feldspar, sodium-rich feldspar, and quartz tend to occur together.  They form light-colored igneous rocks described as felsic.

Felsic Minerals
Typical minerals found in felsic rocks (Photographs by Parvindter Sethi)

Felsic minerals include muscovite (top left), sodium-rich plagioclase feldspar (top right), orthoclase feldspar (bottom left), and quartz (bottom right).  These minerals are light-colored and often occur together in felsic igneous rocks.

GraniteGranite (Photograph by Parvinder Sethi)

Granite, shown here, is an example of a felsic igneous rock.  Light colored grains are quartz and orthoclase feldspar.  Small black crystals are biotite mica.