igneous
Granodiorite
Granodiorite (Intermediate intrusive igneous rock)
Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (mottled gray, white, and black); Luster: Phaneritic (crystalline/vitreous); Crystal Structure: Granular/Massive; Cleavage: None (though constituent minerals like mica and feldspar have it); Specific Gravity: 2.6–2.73
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (mottled gray, white, and black)
- Luster
- Phaneritic (crystalline/vitreous)
Identified More igneous →
Explore Granodiorite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (mottled gray, white, and black); Luster: Phaneritic (crystalline/vitreous); Crystal Structure: Granular/Massive; Cleavage: None (though constituent minerals like mica and feldspar have it); Specific Gravity: 2.6–2.73
Formation & geological history
Formed from the slow cooling of silica-rich magma beneath the Earth's surface (plutonic). It is intermediate in composition between granite and diorite. Often associated with volcanic arc roots and mountain-building subduction zones.
Uses & applications
Used primarily in construction as crushed stone for road base, concrete, and railroad ballast. When polished, it is used for countertops, floor tiles, and ornamental building stone.
Geological facts
Many of the famous monoliths in Yosemite National Park, such as Half Dome, are composed largely of granodiorite rather than true granite. It contains more plagioclase feldspar than orthoclase feldspar.
Field identification & locations
Identify by its coarse-grained 'salt-and-pepper' appearance. Unlike granite, it appears darker due to a higher percentage of mafic minerals (biotite/hornblende). It is commonly found in large batholiths in the Sierra Nevada or the Cascades.
