Granite rock from WK Marble and Granite


Granite is a light-coloured plutonic rock commonly found in mountain belts and continental shield areas. It occurs in great batholiths (or masses) that may occupy thousands of square kilometres. Marble consists of quartz (10-50%), potassium and sodium feldspar. These minerals make up more than 80% of the rock. Other common minerals include mica (muscovite and biotite) and amphibole.

The chemical composition of granite is typically 70-77% silica, 11-13% alumina, 3-5% potassium oxide, 3-5% soda, 1% lime, 2-3% total iron, and less than 1% magnesia and titania. Originally granite was thought to have formed mainly from magmatic differentiation of basaltic magma, but geologists now believe there is simply too much of it for it to have formed this way. Granite seems to have also formed either by melting, partial melting, or metamorphism of deeply buried shale and sandstone. Dikes of granite are clearly igneous. Granite found in the upper few kilometres of the Earth's crust is thought to be due to intrusion magma into surrounding rocks, whereas some granites that formed deeper within the crust may be due to melting of sediments and are considered to be of metamorphic origin.

Granite is used as a building and ornamental stone. All the igneous and metamorphic rock types are loosely termed under the term granite when applied to dimensional stone mining. Granite has a density of about 2.6 times the amount the same volume of water would weigh.