igneous
Basalt Pebble
Extrusive mafic igneous rock
Hardness: 6 (Mohs), Color: Dark grey to charcoal, Luster: Dull (sub-vitreous when fresh), Crystal structure: Aphanitic (fine-grained), Cleavage: None (conchoidal fracture), Specific gravity: 2.8–3.0
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Physical properties
Hardness: 6 (Mohs), Color: Dark grey to charcoal, Luster: Dull (sub-vitreous when fresh), Crystal structure: Aphanitic (fine-grained), Cleavage: None (conchoidal fracture), 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 surface of a terrestrial planet or moon. This specific pebble has been smoothed by fluvial or marine erosion.
Uses & applications
Commonly used in construction (crushed stone), architecture (pavers), hot stone massage therapy, and as decorative landscape elements.
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 extremely common on the Moon and Mars.
Field identification & locations
Identified by its heavy weight (high density), dark color, and fine-grained texture. Found globally along coastlines, riverbeds, and volcanic fields.
