igneous
Vesicular Basalt (Lava Rock)
Aphanitic Mafic Igneous Rock
Hardness: 5-6 (Mohs scale); Color: Dark grey, black, or reddish-brown; Luster: Dull/Earthy; Crystal Structure: Very fine-grained (aphanitic) with vesicular (porous) texture; Specific Gravity: 2.8-3.0
- Hardness
- 5-6 (Mohs scale)
- Color
- Dark grey, black, or reddish-brown
- Luster
- Dull/Earthy
Identified More igneous →
Explore Vesicular Basalt (Lava Rock) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 (Mohs scale); Color: Dark grey, black, or reddish-brown; Luster: Dull/Earthy; Crystal Structure: Very fine-grained (aphanitic) with vesicular (porous) texture; Specific Gravity: 2.8-3.0
Formation & geological history
Formed during volcanic eruptions when lava containing a high concentration of dissolved gases cools rapidly on the Earth's surface. The gas bubbles are trapped as the rock solidifies, creating the characteristic holes or vesicles.
Uses & applications
Used in construction for road base and concrete aggregate, in landscaping as decorative stone, for outdoor gas grills, and as abrasive pumice alternatives.
Geological facts
Basalts are the most common volcanic rock on Earth and also cover much of the surface of the Moon, Mars, and Venus. The vesicles can sometimes later fill with minerals like quartz or calcite to form amygdaloidal basalt.
Field identification & locations
Identified in the field by its dark color, high density (when not too porous), and presence of small, rounded pits or holes. Commonly found in volcanic regions such as Hawaii, Iceland, and the Pacific Northwest.
