Granite

Physical Properties

Hardness: 6-7 Mohs; Color: Mottled cream, tan, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained coarse crystalline); Cleavage: Distinct in feldspar components; Specific gravity: 2.63-2.75

Formation & Geological History

Formed from the slow cooling of silica-rich magma deep underground (plutonic). This process allows large crystals of quartz, feldspar, and mica to grow over millions of years.

Uses & Applications

Primarily used in construction for countertops, flooring, monuments, and curbing due to its durability and aesthetic appeal.

Geological Facts

Granite constitutes a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith in the Black Hills of South Dakota.

Field Identification & Locations

Identify in the field by its speckled 'salt and pepper' appearance and visible interlocking crystals. It is found in mountain ranges and cratons globally, such as the Yosemite Valley.

Identified on: 5/20/2026

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