igneous
Diorite
Diorite (intermediate intrusive igneous rock)
Hardness: 6-7 Mohs; Color: Salt-and-pepper (mottled black and white); Luster: Subvitreous to dull; Crystal structure: Phaneritic (coarsegrained); Composition: Principally plagioclase feldspar, hornblende, and biotite mica.
- Hardness
- 6-7 Mohs
- Color
- Salt-and-pepper (mottled black and white)
- Luster
- Subvitreous 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 Mohs; Color: Salt-and-pepper (mottled black and white); Luster: Subvitreous to dull; Crystal structure: Phaneritic (coarsegrained); Composition: Principally plagioclase feldspar, hornblende, and biotite mica.
Formation & geological history
Formed by the slow cooling of magma deep beneath the Earth's surface (intrusive) in volcanic arcs and mountain building zones (subduction zones). Often Phanerozoic in age.
Uses & applications
Used as a base material in construction of roads and parking lots, as dimension stone for building facades, and as durable sculpture material (famous for the Code of Hammurabi stela).
Geological facts
Diorite is extremely tough and was used by ancient civilizations like the Egyptians and Mesopotamians to create statues and inscriptions because it could be polished to a high luster and was resistant to weather.
Field identification & locations
Look for a medium-to-coarse grained 'salt and pepper' appearance with little to no visible quartz. It is commonly found in the roots of mountain ranges or as river-rounded cobbles in glacial till across North America and Europe.
