igneous
Diorite
Intermediate Phaneritic Igneous Rock
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper appearance (white/light gray feldspar mixed with dark hornblende or pyroxene). Luster: Dull to vitreous. Texture: Phaneritic (medium- to coarse-grained). Cleavage: Good in feldspar grains.
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper appearance (white/light gray feldspar mixed with dark hornblende or pyroxene). Luster: Dull to vitreous. Texture: Phaneritic (medium- to coarse-grained). Cleavage: Good in feldspar grains.
Formation & geological history
Formed by the slow cooling of intermediate magma below the Earth's surface, often in subduction zones and volcanic arcs associated with continental margins.
Uses & applications
Used in construction as crushed stone, dimension stone, building facades, and paving stones. Historically used for carving sculptures and stelae (such as the Code of Hammurabi).
Geological facts
Diorite is often described as having a 'salt-and-pepper' appearance due to its balanced mix of light plagioclase feldspar and dark amphibole/biotite minerals. It was widely used in ancient civilizations because of its durability.
Field identification & locations
Identify in the field by its distinct speckling of white/gray and black mineral grains without significant quartz. Commonly found in mountain belts, batholiths, and beach pebble deposits in volcanic arc regions.
