igneous
Granodiorite
Granodiorite
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (gray, white, black); Luster: Phaneritic (coarse-grained) and crystalline; Structure: Massive, granular; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (gray, white, black)
- Luster
- Phaneritic (coarse-grained) and crystalline
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (gray, white, black); Luster: Phaneritic (coarse-grained) and crystalline; Structure: Massive, granular; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the slow crystallization of silica-rich magma beneath the Earth's surface in batholiths and mountain roots. Typically associated with subduction zones and continental crust formation.
Uses & applications
Used widely in heavy construction, road building, as dimension stone for countertops and flooring, and as crushed stone for railway ballast.
Geological facts
The Rosetta Stone was famously carved from a slab of granodiorite. It is chemically intermediate between granite and diorite, containing more plagioclase feldspar than orthoclase.
Field identification & locations
Identify by its coarse-grained texture and 'salt and pepper' appearance. Unlike granite, it will have significantly more dark minerals like biotite and hornblende and less pinkish potassium feldspar. Common in the Sierra Nevada mountains.
