igneous
Vesicular Basalt
Extrusive Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
Hardness: 5-6 (Mohs scale); Color: Dark grey to dull brown; Luster: Dull/Earthy; Structure: Vesicular (contains many small gas bubbles or pits); Specific Gravity: 2.8 - 3.0
- Hardness
- 5-6 (Mohs scale)
- Color
- Dark grey to dull brown
- Luster
- Dull/Earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Dark grey to dull brown; Luster: Dull/Earthy; Structure: Vesicular (contains many small gas bubbles or pits); Specific Gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface. The 'pits' or vesicles are formed by trapped gas bubbles that escaped as the lava solidified.
Uses & applications
Used primarily in construction (aggregate), road base, and as decorative landscaping stones (lava rocks). High-quality vesicular basalt is also used for 'hot stone' massage therapy due to heat retention.
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 extensively on the Moon and Mars.
Field identification & locations
Identify by its heavy weight (relative to size), dark color, and characteristic 'pitted' surface. Commonly found in volcanic regions, riverbeds near volcanic ranges, and coastal areas.
