Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Grayish-white with black/dark green speckles; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: None (fractures), though component minerals like feldspar have cleavage.

Formation & Geological History

Formed through the slow crystallization of magma below Earth's surface (intrusive). It is a major component of continental crust, found in mountain ranges formed across various geological eras from the Precambrian to Cenozoic.

Uses & Applications

Extensively used in construction as dimension stone for countertops, flooring, curbing, and monuments. Also used as crushed stone for road base and railway ballast.

Geological Facts

Granite makes up a large part of the Earth's continental crust. El Capitan in Yosemite National Park is one of the most famous exposed granite monoliths in the world. It is much harder than marble and resistant to acid.

Field Identification & Locations

Identify in the field by its 'salt and pepper' appearance and large, interlocking crystals of quartz (clear/gray), feldspar (white/pink), and mica or hornblende (black). Found commonly in batholiths and mountain cores.

Identified on: 4/14/2026

Mode: Standard