Granite is an intrusive igneous rock. It forms when magma crystallizes slowly below Earth's surface, resulting in a coarse-grained texture where mineral grains are visible to the naked eye. It is composed mainly of quartz and feldspar (often with mica and amphibole), giving it typical light colors—white, pink, or gray—with darker mineralSpecks from the mafic minerals. [source summaries compiled from standard geology references]