igneous
Basalt (Vesicular/Scoria)
Basalt (Extrusive Mafic Rock)
Hardness: 5-6 (Mohs); Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0; Highly vesicular or pitted surface.
- 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; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0; Highly vesicular or pitted surface.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or moon. Often Cenozoic to recent in age.
Uses & applications
Used as aggregate in construction, for road base, in concrete, and as decorative landscaping stones or grill rocks due to heat retention.
Geological facts
Basalt covers most of the ocean floor and is the most common volcanic rock in the solar system, making up much of the surface of Mars and Venus.
Field identification & locations
Identify by its heavy weight relative to its size (density), dark color, and characteristic 'pitted' or gas-bubble (vesicular) texture. Commonly found in volcanic fields and oceanic islands.
