Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Mottled buff, tan, and dark gray/black. Luster: Dull to phaneritic (visible crystals). Structure: Medium to coarse-grained holocrystalline texture. Composition: High quartz and feldspar content with biotite or hornblende.

Formation & Geological History

Formed by the slow crystallization of magma below Earth's surface (intrusive). They are found in the core of mountain ranges and continental crust, often dating back millions to billions of years.

Uses & Applications

Widely used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as a decorative architectural stone due to its durability.

Geological Facts

Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most resistant rocks used by humans.

Field Identification & Locations

Identify by its interlocking 'salt and pepper' crystalline texture and extreme hardness (cannot be scratched by a steel knife). Common in mountainous regions or glacial deposits.

Identified on: 5/10/2026

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