igneous
Diorite
Diorite
Hardness: 6-7 on Mohs scale; Color: 'Salt and pepper' (black and white/mottled gray); Luster: Sub-vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Composition: Mostly Plagioclase feldspar and Hornblende/Biotite.
- Hardness
- 6-7 on Mohs scale
- Color
- 'Salt and pepper' (black and white/mottled gray)
- Luster
- Sub-vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: 'Salt and pepper' (black and white/mottled gray); Luster: Sub-vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Composition: Mostly Plagioclase feldspar and Hornblende/Biotite.
Formation & geological history
Formed through the slow cooling of magma (intrusive) within the Earth's crust, typically in volcanic arcs and above subduction zones at convergent plate boundaries.
Uses & applications
Used primarily in construction for crushed stone, road base, and as dimension stone for buildings, countertops, and floor tiles. Occasionally used as a base for carvings.
Geological facts
Diorite is often mistaken for granite, but it has little to no quartz. Historically, it was used by ancient civilizations like the Egyptians and Sumerians for sculptures and stelae (such as the Code of Hammurabi) because of its extreme hardness.
Field identification & locations
Identify in the field by its distinctive black and white speckled appearance with visible interlocking crystals and an absence of pinkish potassium feldspar. Commonly found in roots of mountain ranges.
