igneous
Basalt with Vesicles
Vesicular Basalt (Mafic Extrusive)
Hardness: 5-6 Mohs. Color: Reddish-brown to dark gray. Luster: Dull to earthy. Texture: Aphanitic (fine-grained) with small pits or holes (vesicles). Structure: Compact with irregular voids.
- Hardness
- 5-6 Mohs
- Color
- Reddish-brown to dark gray
- Luster
- Dull to earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 Mohs. Color: Reddish-brown to dark gray. Luster: Dull to earthy. Texture: Aphanitic (fine-grained) with small pits or holes (vesicles). Structure: Compact with irregular voids.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the surface. The holes were created by trapped gas bubbles fleeing the lava as it solidified. Red coloration suggests subsequent oxidation (weathering).
Uses & applications
Used primarily in construction as road base, concrete aggregate, and railroad ballast. Small specimens are popular in aquarium decor and landscaping.
Geological facts
Basalt is the most common rock in the Earth's crust and makes up most of the ocean floor. The pitted appearance is technically called 'vesicular' and can eventually fill with other minerals to become 'amygdaloidal'.
Field identification & locations
Identified by its weight (dense for its size), dark base color, and fine-grained texture with visible gas bubbles. Found in volcanic regions globally, such as the Pacific Northwest or Hawaii.
