igneous
Basalt River Stone
Extrusive mafic igneous rock
Hardness (6 on Mohs scale), color is dark grey to black, luster is dull to waxy when wet, fine-grained phaneritic structure, high specific gravity (heavy for its size).
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Physical properties
Hardness (6 on Mohs scale), color is dark grey to black, luster is dull to waxy when wet, fine-grained phaneritic structure, high specific gravity (heavy for its size).
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the earth's surface. This specific specimen has been smooth-tumbled by water action in a river or coastal environment over thousands of years.
Uses & applications
Used in landscaping, high-end construction (as pavers or tiles), hot stone massage therapy, and as decorative gravel.
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 dark color, heavy weight, and absence of visible crystals. It is commonly found in volcanic regions, riverbeds, and along shorelines. Collectors look for unique shapes or 'omars'.
