igneous
Basalt (Pahoehoe texture)
Mafic Volcanic Rock
Hardness: 5-6 (Mohs); Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Aphanitic (fine-grained) with ropy, smooth exterior; Cleavage: None
- Hardness
- 5-6 (Mohs)
- Color
- Dark grey to black
- Luster
- Dull to sub-metallic
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Physical properties
Hardness: 5-6 (Mohs); Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Aphanitic (fine-grained) with ropy, smooth exterior; Cleavage: None
Formation & geological history
Formed from the rapid cooling of low-viscosity, basaltic lava. The ropy 'pahoehoe' texture occurs as the lava flows smoothly beneath a cooling surface skin.
Uses & applications
Used in construction as aggregate, for paving stones, in high-strength floor tiles, and as a raw material for stone wool insulation.
Geological facts
Pahoehoe is a Hawaiian term meaning 'smooth, unbroken lava'. It is the most common rock type on Earth's surface when including the ocean floor.
Field identification & locations
Identify by its glass-smooth or ropy surface and dark color. Common in volcanic hotspots like Hawaii, Iceland, and the Galapagos Islands.
