Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: salt-and-pepper (white, gray, black, with small red specks); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained crystals visible to the naked eye); Specific gravity: 2.63 to 2.75

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface. This specimen shows a typical intrusive texture formed over millions of years within the continental crust.

Uses & Applications

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

Geological Facts

Granite is the most common igneous rock found at Earth's surface and makes up a large portion of the continental crust. It is primarily composed of quartz and feldspar with minor amounts of mica and amphiboles.

Field Identification & Locations

Identify in the field by its speckled 'salt and pepper' appearance and visible interlocking crystals of quartz (clear/gray) and feldspar (white). Often found in mountain ranges and eroded shield areas.

Identified on: 4/17/2026

Mode: Standard