igneous
Granodiorite
Granodiorite (Intermediate intrusive igneous rock)
Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (light grey with dark speckles); Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse crystals visible to the naked eye); Cleavage: Dependent on mineral constituents (feldspar, quartz, biotite).
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (light grey with dark speckles)
- Luster
- Dull to 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 (light grey with dark speckles); Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse crystals visible to the naked eye); Cleavage: Dependent on mineral constituents (feldspar, quartz, biotite).
Formation & geological history
Formed through the slow cooling of magma beneath the Earth's surface (intrusive). It is intermediate in composition between granite and diorite. Found in large batholiths often associated with mountain building events and subduction zones throughout geological history.
Uses & applications
Used extensively in construction as 'crushed stone' for road base and concrete. Higher quality slabs are used for architectural cladding, countertops, paving, and monuments.
Geological facts
Granodiorite is the rock type that makes up the famous Rosetta Stone. It is also the primary component of the Sierra Nevada batholith in California.
Field identification & locations
Identify in the field by its coarse-grained texture and balanced mix of light-colored plagioclase feldspar and dark minerals like biotite or hornblende. It contains more plagioclase than orthoclase, distinguishing it from true granite.
