Granodiorite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled grey, white, and black); Luster: Phaneritic (crystalline/dull); Structure: Coarse-grained intrusive; Cleavage: Dependent on mineral constituents; Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the slow cooling of silica-rich magma beneath the Earth's surface (plutonic). Typically dates from the Archean to the Cenozoic, commonly found in continental batholiths.

Uses & Applications

Used primarily as crushed stone for road construction, building materials, and as ornamenal stone often sold as 'white granite'.

Geological Facts

Granodiorite is the rock that makes up the famous Rosetta Stone. It is intermediate in composition between granite and diorite.

Field Identification & Locations

Identify in the field by its coarse-grained texture and the presence of more plagioclase feldspar than orthoclase. Commonly found in mountain ranges such as the Sierra Nevada.

Identified on: 4/29/2026

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