Granite

Physical Properties

Hardness (Mohs scale): 6 to 7; Color: Pink, light gray, and black speckled (salt and pepper); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63 to 2.75

Formation & Geological History

Formed from the slow crystallization of magma below the Earth's surface (intrusive). Composed primarily of quartz, feldspar, and mica. It is typically found in continental crust and can be millions or billions of years old.

Uses & Applications

A major construction material used for kitchen countertops, flooring, monuments, paving stones, and curbings. It is also used as crushed stone in road base and railway ballast.

Geological Facts

Granite is the most common igneous rock found on Earth's surface. Mount Rushmore and the Egyptian pyramids contain significant amounts of granite. It is an extremely durable stone that can last for centuries.

Field Identification & Locations

Identify in the field by its speckled appearance and visible interlocking crystals of pink/white feldspar and clear quartz. Often found in mountainous regions or areas with exposed continental shields. Collectors look for large crystals or unique color patterns.

Identified on: 4/29/2026

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