igneous
River Stone (likely Basalt or fine-grained Andesite)
Extrusive Igneous Rock (Mafic to Intermediate)
Hardness (6-7 Mohs), dark grey to olive-brown color, dull to earthy luster, fine-grained (aphanitic) texture, high density (2.8-3.0 SG), smooth rounded shape from water erosion.
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Physical properties
Hardness (6-7 Mohs), dark grey to olive-brown color, dull to earthy luster, fine-grained (aphanitic) texture, high density (2.8-3.0 SG), smooth rounded shape from water erosion.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. This specific specimen has been significantly smoothed and rounded over time by the mechanical action of water in a river or coastal environment.
Uses & applications
Commonly used in landscaping, construction (as aggregate), decorative water features, and for massage therapy (hot stones due to heat retention).
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 on the Moon and Mars.
Field identification & locations
Identify by its heavy weight relative to size, fine-grained surface with occasional small pits (vesicles), and rounded edges. Found globally in riverbeds, beaches, and volcanic regions.
