igneous
Diorite
Diorite (plagioclase feldspar, biotite, and hornblende)
Hardness: 6-7 on Mohs scale; Color: 'Salt and pepper' (mottled black/dark green and white/grey); Luster: Sub-vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0
- Hardness
- 6-7 on Mohs scale
- Color
- 'Salt and pepper' (mottled black/dark green and white/grey)
- Luster
- Sub-vitreous to dull
Identified More igneous →
Explore Diorite 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 black/dark green and white/grey); Luster: Sub-vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0
Formation & geological history
Formed by the slow cooling of magma beneath the Earth's surface in volcanic arches or subduction zones. It represents an intermediate composition between felsic granite and mafic gabbro.
Uses & applications
Primarily used in construction as crushed stone for roads or structural foundations; historically used for monumental carvings and polished decorative stone.
Geological facts
The Code of Hammurabi, one of the oldest legal codes in history, was inscribed on a massive black diorite stele. It is often confused with granite but lacks significant translucent quartz.
Field identification & locations
Identify by its distinct medium-to-coarse mottle pattern with roughly equal amounts of dark and light minerals. Commonly found in roots of mountain ranges or as eroded river stones.
