igneous
Granodiorite
Granodiorite
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (gray, white, pink, black); Luster: Phaneritic (crystalline); Crystal structure: Granular/Coarse-grained; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 (Mohs scale)
- Color
- Salt and pepper (gray, white, pink, black)
- Luster
- Phaneritic (crystalline)
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (gray, white, pink, black); Luster: Phaneritic (crystalline); Crystal structure: Granular/Coarse-grained; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the slow cooling and crystallization of magma deep beneath the Earth's surface (plutonic). Found in batholiths and mountain ranges, often associated with subduction zones.
Uses & applications
Used primarily as road base, construction aggregate, paving stones, and countertop material (often sold commercially as 'granite').
Geological facts
Granodiorite is the rock that makes up the famous Rosetta Stone. It is intermediate in composition between granite and diorite, containing more plagioclase feldspar than orthoclase.
Field identification & locations
Identify by its coarse-grained texture and visual balance of light minerals (quartz/feldspar) and dark minerals (biotite/hornblende). It is ubiquitous in the Sierra Nevada mountains and other continental arc systems.
