familygranitic

Familygranitic is a term used in petrology to describe rocks that belong to the granitoid family, a group of felsic, silica-rich igneous rocks that are commonly coarse-grained and quartz- and feldspar-dominated. The term emphasizes shared origin and mineralogy with granite while allowing inclusion of closely related granitoid lithologies.

Mineralogy and texture: The typical mineral assemblage includes quartz, alkali feldspar, and plagioclase, with minor mica, hornblende, or other ferromagnesian minerals. Accessory minerals such as zircon and apatite are common. Textures are usually phaneritic and coarse-grained, reflecting slow cooling within the crust; some specimens show porphyritic or pegmatitic textures.

Formation and occurrence: Familygranitic rocks crystallize from silica-rich magmas produced by partial melting of crustal rocks or differentiation of magmas in deep crustal chambers. They form large intrusive bodies such as batholiths and plutons and are widely exposed in continental shield regions and active or former orogenic belts.

Classification and notes: The term is not universally standardized and is encountered mainly in older literature or in discussions of granitoid suites. In modern practice, rocks in the granitoid family are more often referred to as granitoids or by specific lithologies such as granite or granodiorite.

Related topics include granite, granitoid, and felsic intrusive rocks.