igneous
Granodiorite (containing Biotite and Quartz)
Granodiorite (Plagioclase-rich phaneritic intrusive rock)
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled grey, black, and white); Luster: Vitreous to dull; Structure: Phaneritic (coarse-grained crystals); Cleavage: Distinct in feldspars, none in quartz.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (mottled grey, black, and white)
- Luster
- Vitreous to dull
Identified More igneous →
Explore Granodiorite (containing Biotite and Quartz) 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 grey, black, and white); Luster: Vitreous to dull; Structure: Phaneritic (coarse-grained crystals); Cleavage: Distinct in feldspars, none in quartz.
Formation & geological history
Formed through the slow cooling of silica-rich magma beneath the Earth's surface (plutonic). Typically found in batholiths within continental crust and subduction zones.
Uses & applications
Used extensively in construction as 'granite' for countertops, paving stones, and road base construction. Also used in monumental architecture.
Geological facts
Granodiorite is the rock that makes up the famous Rosetta Stone. It is chemically transitional between granite and diorite, containing more plagioclase than orthoclase feldspar.
Field identification & locations
Identify in the field by its coarse crystalline texture where white/grey plagioclase exceeds pinkish orthoclase, mixed with black biotite or hornblende. Commonly found in mountain ranges like the Sierra Nevada.
