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A felsic volcanic rock fragment, as seen in a petrographic microscope. Scale box is in millimeters

Close-up of granite from Yosemite National Park

A specimen of Rhyolite

The word "felsic" is a term used in geology to refer to silicate minerals, magma, and igneous rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.

They are usually light in colour and have specific gravities less than 3. The most common felsic rock is granite, but others include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars. In terms of chemistry, felsic rocks are on the other side of the rock spectrum from the mafic rocks. view more...