igneous
Granodiorite
Granodiorite
Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (white, gray, and black); Luster: Phaneritic (crystalline); Crystal Structure: Granular/Coarse-grained; Cleavage: Varies by mineral constituent; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (white, gray, and black)
- Luster
- Phaneritic (crystalline)
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (white, gray, and black); Luster: Phaneritic (crystalline); Crystal Structure: Granular/Coarse-grained; Cleavage: Varies by mineral constituent; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the slow cooling of silica-rich magma beneath the Earth's surface (intrusive). They typically occur in large batholiths associated with mountain building along subduction zones.
Uses & applications
Major use in construction as crushed stone or 'granite' slabs for countertops, building facades, and paving stones. Is also used for monuments and statues.
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 'salt and pepper' look; look for visible crystals of quartz, plagioclase, and dark biotite or hornblende. It is frequently found in the Sierra Nevada and other major mountain ranges.
