igneous
Granodiorite
Granodiorite
Hardness: 6-7 on Mohs scale; Color: Gray to pinkish-gray with salt-and-pepper texture; Luster: Dull (weathered) to vitreous (fresh); Crystal Structure: Phaneritic (medium to coarse-grained); Cleavage: Dependent on mineral (feldspar/mica); Specific Gravity: 2.6-2.8
- Hardness
- 6-7 on Mohs scale
- Color
- Gray to pinkish-gray with salt-and-pepper texture
- Luster
- Dull (weathered) to vitreous (fresh)
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Gray to pinkish-gray with salt-and-pepper texture; Luster: Dull (weathered) to vitreous (fresh); Crystal Structure: Phaneritic (medium to coarse-grained); Cleavage: Dependent on mineral (feldspar/mica); Specific Gravity: 2.6-2.8
Formation & geological history
Formed through the slow cooling of silica-rich magma beneath the Earth's surface (intrusive). They occur in large plutons or batholiths, often along convergent plate boundaries. Many are hundreds of millions of years old.
Uses & applications
Used widely as crushed stone for road construction, paving, and as architectural dimension stone (countertops, monuments) similar to 'commercial granite'.
Geological facts
Granodiorite is the rock that makes up the famous Rosetta Stone. It has a slightly higher concentration of dark minerals (biotite/hornblende) and plagioclase feldspar than true granite.
Field identification & locations
Identify by its interlocking crystalline texture and 'salt and pepper' appearance. Look for the presence of white/gray plagioclase, quartz, and dark specks of biotite or hornblende. It is common in mountain belts like the Sierra Nevada.
