igneous
Basalt Pebble
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, dark gray to black in color, dull to sub-mettalic luster, fine-grained (aphanitic) crystal structure, specific gravity around 2.8-3.0.
Identified More igneous →
Explore Basalt Pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 6 on the Mohs scale, dark gray to black in color, dull to sub-mettalic luster, fine-grained (aphanitic) crystal structure, specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the Earth's surface.
Uses & applications
Used in construction, road aggregate, railroad ballast, and sometimes for decorative landscaping or hot stone massage therapy.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins and is also found abundantly on the Moon and Mars.
Field identification & locations
Easily identified by its dark, dense, fine-grained appearance, often rounded by water action in rivers or beaches. Common globally in volcanic regions.
