What is granite?
Granite is an igneous rock that is composed of four minerals. These minerals are quartz, feldspar, mica, and usually hornblende. Granite forms as magma cools far under the earth's surface. Because it hardens deep underground it cools very slowly. This allows crystals of the four minerals to grow large enough to be easily seen by the naked eye.
Granite - 2:
A coarse-grained intrusive igneous rock with at least 65% silica. Quartz, plagioclase feldspar and potassium feldspar make up most of the rock and give it a fairly light color. Granite has more potassium feldspar than plagioclase feldspar. Usually with biotite, but also may have hornblende.
Granite - 3:
An intrusive igneous rock, granite is a felsic rock with dominant minerals -- orthoclase (a pink, potassium-rich variety of feldspar), quartz, and lesser amounts of mica (both silvery muscovite or black biotite), hornblende, and plagioclase (white to gray,sodium-rich varieties of feldspar). Note that the word 'granite' is used fairly liberally. Many rocks called 'granite' are technically something different. The word 'granitoid' or 'granitic' implies felsic to intermediate intrusive rocks of many varieties, including granite.