igneous
Vesicular Basalt
Basalt (with vesicular texture)
Hardness: 5-6 Mohs. Color: dark gray to black, often weathering to brown. Luster: dull to earthy. Texture: vesicular (pitted with gas bubble holes). Crystal structure: fine-grained (aphanitic).
- Hardness
- 5-6 Mohs
- Color
- dark gray to black, often weathering to brown
- Luster
- dull to earthy
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Physical properties
Hardness: 5-6 Mohs. Color: dark gray to black, often weathering to brown. Luster: dull to earthy. Texture: vesicular (pitted with gas bubble holes). Crystal structure: fine-grained (aphanitic).
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The pits or 'vesicles' are formed by gas bubbles that were trapped in the lava as it solidified.
Uses & applications
Used primarily in construction as aggregate for roads and concrete, in landscaping as decorative 'lava rock', and in grilling (lava rocks for gas grills).
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (high specific gravity), and the presence of small holes or pits. It is found in volcanic regions worldwide, such as Hawaii, Iceland, and the Pacific Northwest.
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Dark Igneous Rock (Likely Basalt or Diabase)
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