Pronunciation: GRAN•it
Description*:
Granite is an intrusive igneous rock composed primarily of alkalai feldspar (e.g., the potassium-rich feldspar orthoclase, which commonly has a salmon pink color), sodium-rich plagioclase feldspar (which is commonly white to gray), and quartz (which is commonly colorless). Granite commonly has a phaneritic (medium- to coarse-grained) to phaneritic-porphyritic (with some large crystals) texture. Granites and rhyolites commonly have a pinkish tone due to the pink potassium feldspar. Granite and rhyolite are said to be felsic (or sialic) rocks because of their light tone, in contrast to the dark tone of the mafic rocks basalt and gabbro.
Granite forms in continental crust above subduction zones, commonly along with diorite.
*Description from Cronin, V.S., 2001, Geology laboratory projects for group learning: Primis McGraw-Hill, 156 pp., ISBN 0-07-252348-4
Used by permission of the author.
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