igneous
Granodiorite
Phaneritic Plutonic Rock (Intermediate)
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled grey/white/black); Luster: Vitreous to dull; Crystal structure: Phaneritic (medium to coarse-grained); Specific gravity: 2.6-2.7
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (mottled grey/white/black)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled grey/white/black); Luster: Vitreous to dull; Crystal structure: Phaneritic (medium to coarse-grained); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the slow crystallization of magma beneath the Earth's surface. It is typical of continental crust and often forms in volcanic arcs and mountain-building regions over millions of years.
Uses & applications
Used widely in heavy construction, road building, as crushed stone, and as a polished dimension stone for countertops and architectural cladding.
Geological facts
Granodiorite is the rock type that makes up the famous Rosetta Stone. It is chemically intermediate between granite and diorite, containing more plagioclase feldspar than orthoclase.
Field identification & locations
Identify by looking for a speckled 'salt and pepper' appearance with crystals visible to the naked eye. It is found in large batholiths globally, such as the Sierra Nevada in California.
