igneous
Diorite
Intermediate plutonic igneous rock
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper appearance due to a mix of light plagioclase feldspar and dark minerals like hornblende and biotite. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained). Specific gravity: 2.8-3.0.
- Hardness
- 6-7 on Mohs scale
- Luster
- 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 appearance due to a mix of light plagioclase feldspar and dark minerals like hornblende and biotite. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained). Specific gravity: 2.8-3.0.
Formation & geological history
Formed from the slow cooling of magma beneath the Earth's surface, typically containing intermediate amounts of silica. Common in subduction zone settings, often associated with continental volcanic arcs.
Uses & applications
Used widely in construction and architecture as crushed stone, dimension stone, and decorative aggregate. Historically used for ancient carvings such as the Code of Hammurabi.
Geological facts
Diorite is extremely hard and tough to work with, which is why ancient civilizations prized it for monuments. It is compositionally intermediate between granite and gabbro.
Field identification & locations
Easily identified in the field by its distinct salt-and-pepper texture lacking the significant quartz content of granite. Commonly found in mountain belts worldwide.
