Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Pink, white, and black speckled (salt and pepper); Luster: Vitreous to dull; Crystal structure: Phaneritic (visible crystals of quartz, feldspar, and mica); Specific Gravity: 2.63 - 2.75

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface. High in silica, it forms major parts of the continental crust and occurs in massive batholiths. Ages can range from Precambrian to Cenozoic.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, and monuments. Also used as crushed stone for road base and railroad ballast.

Geological Facts

Granite is one of the hardest substances in the world, second only to diamonds. It makes up a large portion of the continental crust and is famously found forming the peaks of the Yosemite Valley and Mount Rushmore.

Field Identification & Locations

Identify by its 'salt and pepper' appearance with visible grains. Look for chunky pink or white feldspar, glassy gray quartz, and black flecks of biotite or hornblende. It is ubiquitous in glacial till and riverbeds across the Northern Hemisphere.

Identified on: 4/24/2026

Mode: Standard