Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, gray, and black. Luster: Vitreous to dull. Crystal structure: Phaneritic (visible coarse-grained crystals). Cleavage: Varies by mineral constituent (Feldspar has good cleavage, Quartz has none).

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface (intrusive). This process often occurs over millions of years within the continental crust, primarily during orogenic (mountain-building) events.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, and curbing. It is also used for monuments, gravestones, and as decorative aggregate in landscaping.

Geological Facts

Granite makes up a large portion of the Earth's continental crust. Unlike oceanic crust which is basaltic, the 'buoyancy' of granite allows continents to sit higher on the mantle. Famous landmarks like Yosemite's Half Dome and Mount Rushmore are made of granite.

Field Identification & Locations

Identify in the field by its coarse-grained 'salt and pepper' appearance and the presence of glassy quartz alongside salmon-pink or white feldspar. It is commonly found in mountainous regions or where ancient shield rocks are exposed.

Identified on: 4/22/2026

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