igneous
Diorite (possibly Orbicular Diorite or Porphyritic Diorite)
Intermediate Phaneritic Igneous Rock
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (mottled grey, white, and black); Luster: Dull to sub-vitreous; Structure: Phaneritic (coarse-grained); Specific Gravity: 2.8 - 3.0
- Hardness
- 6-7 (Mohs scale)
- Color
- Salt and pepper (mottled grey, white, and black)
- Luster
- Dull to sub-vitreous
Identified More igneous →
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (mottled grey, white, and black); Luster: Dull to sub-vitreous; Structure: Phaneritic (coarse-grained); Specific Gravity: 2.8 - 3.0
Formation & geological history
Formed by the slow cooling of silicate magma below the Earth's surface, often in volcanic arcs and mountain-building zones. This specimen appears water-worn or tumbled into a cobble shape.
Uses & applications
Used as a crushed stone for base material in road construction, as dimension stone for building facades, or polished for use as countertops and floor tiles.
Geological facts
Diorite was used by ancient civilizations, such as the Babylonians, to carve durable statues and stelae, including the famous Code of Hammurabi.
Field identification & locations
Identify by its salt-and-pepper appearance with roughly equal parts light (plagioclase feldspar) and dark (hornblende/biotite) minerals. Look for it in glacial till or riverbeds near igneous mountain ranges.
