igneous
Granodiorite
Granodiorite
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (mottled grey, white, and black); Luster: Phaneritic/Crystalline; Crystal Structure: Coarse-grained intrusive; Specific Gravity: 2.6-2.73.
- Hardness
- 6-7 (Mohs scale)
- Color
- Salt and pepper (mottled grey, white, and black)
- Luster
- Phaneritic/Crystalline
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (mottled grey, white, and black); Luster: Phaneritic/Crystalline; Crystal Structure: Coarse-grained intrusive; Specific Gravity: 2.6-2.73.
Formation & geological history
Formed through the slow cooling of silica-rich magma deep underground. It is an intrusive igneous rock intermediate between granite and diorite, common in volcanic arcs and mountain roots.
Uses & applications
Used widely in construction as crushed stone for road base, building stone (similar to granite), countertops, and pavers. It is valued for its durability and aesthetic similarity to granite.
Geological facts
Granodiorite is the rock type that makes up the famous Rosetta Stone. It is also a primary component of the continental crust and forms large batholiths like those in the Sierra Nevada mountains.
Field identification & locations
Identify in the field by its coarse-grained 'salt and pepper' appearance and high presence of plagioclase feldspar over alkali feldspar. It is commonly found in large mountain ranges formed by tectonic subduction.
