igneous
Diorite (weathered)
Intermediate plutonic igneous rock
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled black/white/grey/green) with brown iron staining; Luster: Dull to phaneritic; Structure: Granular/Crystalline; Cleavage: Good in feldspar crystals.
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to phaneritic
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled black/white/grey/green) with brown iron staining; Luster: Dull to phaneritic; Structure: Granular/Crystalline; Cleavage: Good in feldspar crystals.
Formation & geological history
Formed through the slow cooling of magma below the Earth's surface in volcanic arcs or orogenic belts. This specific specimen shows oxidative weathering (rust-colored staining) from exposure to air and water.
Uses & applications
Used primarily in construction as crushed stone or 'road base'. High-quality varieties are polished for use as architectural stone, countertops, or cemetery monuments.
Geological facts
Diorite was used by Ancient Egyptians for statues and vases because of its extreme hardness and durability; the Code of Hammurabi was famously inscribed on a diorite stele.
Field identification & locations
Identify by its coarse-grained 'salt and pepper' appearance and lack of visible quartz compared to granite. It is commonly found in mountain ranges such as the Andes, or across the Cascades in the US.
