igneous
Diorite (with Quartz veins)
Diorite
AI-generated identification · may be incorrectHardness: 6-7 (Mohs scale); Color: Black and white 'salt and pepper' appearance; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0.
- Hardness
- 6-7 (Mohs scale)
- Color
- Black and white 'salt and pepper' appearance
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Black and white 'salt and pepper' appearance; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0.
Formation & geological history
Formed through the slow cooling of magma beneath the Earth's surface (intrusive). Usually found in volcanic arcs and mountain-building regions associated with subduction zones.
Uses & applications
Used primarily as crushed stone for road construction, drainage, and foundation fill. High-quality specimens are polished for use as dimension stone, countertops, and floor tiles.
Geological facts
Diorite was used by ancient civilizations, such as the Egyptians and Sumerians, for making statues and stelae because of its extreme hardness; the Code of Hammurabi was famously inscribed on a diorite stele.
Field identification & locations
Identify in the field by its distinctive 'salt and pepper' look, consisting of white plagioclase feldspar and dark hornblende/biotite. It is found in large mountain ranges such as the Andes or the Cascades.
