igneous
Vesicular Basalt
Basalt (Mafic Extrusive)
Hardness: 5-6 Mohs. Color: Black to dark gray. Luster: Dull to sub-metallic. Texture: Vesicular (contains air bubbles/holes) and fine-grained (aphanitic). Composition: Plagioclase feldspar, pyroxene, and olivine.
- Hardness
- 5-6 Mohs
- Color
- Black to dark gray
- Luster
- Dull to sub-metallic
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Physical properties
Hardness: 5-6 Mohs. Color: Black to dark gray. Luster: Dull to sub-metallic. Texture: Vesicular (contains air bubbles/holes) and fine-grained (aphanitic). Composition: Plagioclase feldspar, pyroxene, and olivine.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The holes (vesicles) were created by gas bubbles trapped in the cooling lava.
Uses & applications
Construction aggregate, road base, paving stones, and as a component in stonemasonry or landscaping. High-quality specimens are used in aquarium decor.
Geological facts
Basalt is the most common volcanic rock on Earth and also makes up the majority of the ocean floor. It is found on the Moon and Mars as well.
Field identification & locations
Identify by its characteristic dark color, heavy weight (high specific gravity), and pitted surface. Commonly found in volcanic regions or as water-worn cobbles on beaches near ancient lava flows.
