igneous
Diorite
Intermediate plutonic igneous rock
Hardness: 6-7 on Mohs scale. Color: Salt and pepper appearance with contrasting black and white crystals. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained, visible interlocking crystals). Specific gravity: 2.7-2.9.
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt and pepper appearance with contrasting black and white crystals. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained, visible interlocking crystals). Specific gravity: 2.7-2.9.
Formation & geological history
Formed from the slow cooling of magma rich in silica, plagioclase feldspar, and dark amphibole or biotite minerals beneath the Earth's surface.
Uses & applications
Commonly used in construction, as crushed stone for road bases, and historically as a carving stone by ancient civilizations (such as the Code of Hammurabi).
Geological facts
Ancient Egyptians and Mesopotamians frequently used diorite for statues and vessels because of its extreme toughness and resistance to weathering.
Field identification & locations
Easily identified in the field by its distinct 'salt and pepper' look, composed mainly of white plagioclase feldspar and dark hornblende. Commonly found in subduction zone mountain belts.
