igneous
Basalt (Beach Pebble)
Basalt
Hardness 6-6.5, dark green to black color, smooth water-worn texture, vitreous to dull luster when wet, fine-grained microcrystalline texture.
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Physical properties
Hardness 6-6.5, dark green to black color, smooth water-worn texture, vitreous to dull luster when wet, fine-grained microcrystalline texture.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface. Rounded and polished over time by wave action on the beach.
Uses & applications
Used in landscaping, aquariums, decorative pebble gardens, and aggregate in construction.
Geological facts
Basalt is the most common rock type in the Earth's crust, making up most of the oceanic floor and volcanic island arcs.
Field identification & locations
Identified by its dark coloration, heavy density relative to size, fine-grained texture, and smooth, rounded shape caused by water erosion.
