igneous
Basalt Pebble
Basalt
Hardness: 6 (Mohs scale), Color: Dark grey to black with brownish weathering, Luster: Dull to earthy, Crystal Structure: Aphanitic (fine-grained), Cleavage: None, Specific Gravity: 2.8 - 3.0
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Physical properties
Hardness: 6 (Mohs scale), Color: Dark grey to black with brownish weathering, Luster: Dull to earthy, Crystal Structure: Aphanitic (fine-grained), Cleavage: None, 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 Earth's surface. This specimen appears water-worn, likely tumbled in a river or coastal environment.
Uses & applications
Used primarily in construction as crushed stone for road base, concrete aggregate, and railroad ballast. Small pebbles are often used in landscaping or aquarium decor.
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 found moon and Mars.
Field identification & locations
Identify by its dark color, fine grain, and weight (denser than most common rocks). Found worldwide in volcanic regions or in alluvial deposits like riverbeds.
