GEOLOGY & PLANETARY SCIENCE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site granite In this sample of granite, the pink crystals are potassium feldspar, much of the white or clear crystals are quartz, and the black crystals are mica An extremely hard, light-colored, acidic igneous rock consisting mainly of plagioclase feldspar and quartz (average 25%), with some biotite (mica), hornblende, and other colored material. Granite generally results from the slow solidification of magma deep within the crust (2 to 50 km) in large batholiths; i.e., it is an intrusive rock. The slow cooling gives a coarse grain size. Some granites result from metamorphism of pre-existing rocks.    • GEOLOGY AND PLANETARY SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP