igneous
Diorite
Diorite (Intermediate intrusive igneous rock)
Hardness: 6 to 7 on the Mohs scale. Color: Mottled black and white (salt and pepper appearance). Luster: Phaneritic (crystalline) and somewhat dull to sub-vitreous. Structure: Coarse-grained intrusive. Specific Gravity: 2.8 to 3.0.
- Hardness
- 6 to 7 on the Mohs scale
- Color
- Mottled black and white (salt and pepper appearance)
- Luster
- Phaneritic (crystalline) and somewhat dull to sub-vitreous
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Physical properties
Hardness: 6 to 7 on the Mohs scale. Color: Mottled black and white (salt and pepper appearance). Luster: Phaneritic (crystalline) and somewhat dull to sub-vitreous. Structure: Coarse-grained intrusive. Specific Gravity: 2.8 to 3.0.
Formation & geological history
Formed through the slow cooling of magma below the Earth's surface in volcanic arcs and mountain building zones. It is commonly associated with subduction zones and can range in age from Precambrian to Cenozoic.
Uses & applications
Used in construction as crushed stone for road base and drainage. In polished form, it is used for building facades, floor tiles, and cemetery markers (similar to granite).
Geological facts
Diorite was used in ancient Egypt and Mesopotamia for sculptures due to its hardness and durability. The famous Code of Hammurabi was inscribed on a diorite stele.
Field identification & locations
Identify by its 'salt and pepper' look, where dark minerals (biotite/amphibole) and light minerals (plagioclase feldspar) are present in roughly equal amounts. It lacks the pinkish potassium feldspar or high quartz content of granite.
