igneous
Diorite
Diorite (Intermediate intrusive igneous rock)
Hardness: 6-7 (Mohs scale), Color: 'Salt and pepper' (mottled black and white), Luster: Phaneritic (crystalline), Structure: Coarse-grained granular, Specific gravity: 2.8-3.0.
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Physical properties
Hardness: 6-7 (Mohs scale), Color: 'Salt and pepper' (mottled black and white), Luster: Phaneritic (crystalline), Structure: Coarse-grained granular, Specific gravity: 2.8-3.0.
Formation & geological history
Formed by the slow cooling of intermediate silicate magma beneath the Earth's surface in volcanic arcs or subduction zones. It represents a composition between granite and gabbro.
Uses & applications
Commonly used as a base material in road construction, as crushed stone for building foundations, and historically as a medium for sculpture and architectural facings due to its durability.
Geological facts
The Code of Hammurabi was inscribed on a massive stele of black diorite. It is one of the toughest stones to carve, making it highly valued by ancient Egyptian and Mesopotamian sculptors.
Field identification & locations
Identify in the field by its characteristic speckled appearance (salt and pepper), lack of visible quartz (unlike granite), and coarse crystalline texture. Commonly found in roots of mountain ranges.
