Granodiorite / Granite

Physical Properties

Hardness: 6-7 (Mohs scale); Color: Grayish-white with dark speckles (salt and pepper appearance); Luster: Phaneritic (crystalline) and somewhat dull; Crystal Structure: Coarse-grained intrusive; Cleavage: None (fractures irregularly); Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the slow cooling of silica-rich magma deep underground (plutonic). This process allows large crystals to form. Specimens like this can range from millions to billions of years old, common in continental crust mountain belts.

Uses & Applications

Broadly used in construction as crushed stone, road base, and architectural building stone. High-quality slabs are used for countertops and monuments.

Geological Facts

Granodiorite is the most common rock found in the Earth's continental crust. Famous landmarks like the Rosetta Stone and the base of the Statue of Liberty are carved from granodiorite or similar granitic rocks.

Field Identification & Locations

Identify by its 'salt and pepper' look where you can see individual interlocking crystals of white/clear quartz and dark minerals. Common in batholiths and mountain ranges like the Sierra Nevada. It is very hard and will scratch glass.

Identified on: 4/26/2026

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