igneous
Diorite
Intermediate plutonic igneous rock
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper appearance consisting of black/dark green amphibole or pyroxene and white/grey plagioclase feldspar. Luster: Vitreous to dull. Texture: Phaneritic (coarse-grained). Cleavage: Present in constituent minerals.
- 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 consisting of black/dark green amphibole or pyroxene and white/grey plagioclase feldspar. Luster: Vitreous to dull. Texture: Phaneritic (coarse-grained). Cleavage: Present in constituent minerals.
Formation & geological history
Formed by the slow cooling of intermediate magma underground in subduction zones, continental arcs, and mountain-building regions.
Uses & applications
Used as crushed stone for construction, road bases, dimension stone for buildings, countertops, and historically for carving statues due to its durability.
Geological facts
Diorite is so hard that ancient civilizations, including the Egyptians and Babylonians, used it to carve durable inscriptions and statues; the famous Code of Hammurabi stele is carved into diorite.
Field identification & locations
Identified in the field by its distinct speckling ('salt and pepper' texture) and absence or extreme scarcity of quartz compared to granite. Commonly found in mountain belts and volcanic arcs worldwide.
