igneous
Granodiorite
Granodiorite (containing Plagioclase, Quartz, Orthoclase, Biotic/Hornblende)
Hardness: 6-7 Mohs; Color: Salt and pepper (white/grey with black speckles); Luster: Phaneritic (crystalline); Structure: Massive, granular; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 Mohs
- Color
- Salt and pepper (white/grey with black speckles)
- Luster
- Phaneritic (crystalline)
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper (white/grey with black speckles); Luster: Phaneritic (crystalline); Structure: Massive, granular; Specific Gravity: 2.6-2.7
Formation & geological history
Formed by the slow cooling of silica-rich magma beneath the Earth's surface in continental crust environments, typically in volcanic arcs and mountain building zones.
Uses & applications
Used widely in construction as crushed stone, road grade, and as ornamental building stone (sold commercially as 'white granite' for countertops and flooring).
Geological facts
Granodiorite is the intermediate rock between granite and diorite. The famous Rosetta Stone was carved from a slab of granodiorite, not basalt as originally thought.
Field identification & locations
Identify by looking for a coarse-grained texture where the white/grey plagioclase feldspar crystals outnumber the pinkish orthoclase. Found in large batholiths like the Sierra Nevada.
