igneous
Granodiorite
Granodiorite
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (shades of grey, white, and black); Luster: Phaneritic (medium to coarse-grained crystalline); Structure: Massive plutonic; Components: Quartz, plagioclase feldspar, biotite, and hornblende.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (shades of grey, white, and black)
- Luster
- Phaneritic (medium to coarse-grained crystalline)
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (shades of grey, white, and black); Luster: Phaneritic (medium to coarse-grained crystalline); Structure: Massive plutonic; Components: Quartz, plagioclase feldspar, biotite, and hornblende.
Formation & geological history
Formed through the slow cooling of silica-rich magma deep within the Earth's crust, often in volcanic arcs above subduction zones. This specimen appears water-worn, likely from a river or beach environment.
Uses & applications
Used primarily as crushed stone for road construction and as dimension stone for building facades, countertops, and monuments.
Geological facts
Granodiorite is the intermediate rock between granite and diorite. The famous Rosetta Stone was carved from a slab of granodiorite.
Field identification & locations
Identify by its 'salt and pepper' appearance with a higher concentration of dark minerals (biotite/hornblende) compared to true granite. Look for the presence of visible quartz grains alongside white feldspar. Commonly found in batholiths and mountain ranges like the Sierra Nevada.
