igneous
Vesicular Basalt
Vesicular Basalt (Mafic Volcanic Rock)
Hardness: 5-6 Mohs. Color: Gray, tan, or brown (due to weathering). Luster: Dull/Earthy. Texture: Vesicular (containing pits/gas bubbles). Composition: Plagioclase feldspar, pyroxene, and olivine.
- Hardness
- 5-6 Mohs
- Color
- Gray, tan, or brown (due to weathering)
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 Mohs. Color: Gray, tan, or brown (due to weathering). Luster: Dull/Earthy. Texture: Vesicular (containing pits/gas bubbles). Composition: Plagioclase feldspar, pyroxene, and olivine.
Formation & geological history
Formed from extrusive volcanic activity where rapid cooling of lava traps gas bubbles, creating a porous texture. Typically Cenozoic to recent in many volcanic fields.
Uses & applications
Used in landscaping, construction aggregate, railroad ballast, and sometimes as a natural abrasive (pumice-like) for stone-washing textiles.
Geological facts
The holes in this rock, called vesicles, are effectively 'frozen' gas bubbles that were trying to escape the lava as it solidified on the Earth's surface.
Field identification & locations
Identify by its light weight relative to size (due to air pockets) and the presence of small spherical or oval pits. Commonly found in volcanic regions like the Pacific Northwest, Hawaii, or Iceland.
