igneous
Basalt Pebble (Beach Stone)
Basalt (Mafic Extrusive Igneous Rock)
Hardness: 6 (Mohs scale), Color: Dark greenish-grey to black, Luster: Dull to resinous/waxy when wet, Texture: Fine-grained (aphanitic), Specific gravity: 2.8 - 3.0
Identified More igneous →
Explore Basalt Pebble (Beach Stone) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6 (Mohs scale), Color: Dark greenish-grey to black, Luster: Dull to resinous/waxy when wet, Texture: Fine-grained (aphanitic), Specific gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. Water-worn and rounded through river or beach wave erosion.
Uses & applications
Commonly used as construction aggregate, crushed stone for road bases, landscaping pebbles, and aquarium decoration.
Geological facts
Basalt is the most common rock type in the Earth's crust, making up most of the oceanic crust as well as large volcanic plateaus on land.
Field identification & locations
Identified by its dark color, heavy weight relative to size, fine-grained smooth texture, and water-rounded oval pebble shape on beaches.
