igneous
Small dark, water-worn pebble (likely basalt)
Basalt, a fine-grained mafic volcanic rock; identification is uncertain from the blurry image
AI-generated identification · may be incorrectAppears dark gray to black and smooth, with a rounded, possibly water-worn surface. Basalt commonly has Mohs hardness 5–6, a fine-grained texture, and a dull to slightly waxy luster; individual crystals are usually too small to see.
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Physical properties
Appears dark gray to black and smooth, with a rounded, possibly water-worn surface. Basalt commonly has Mohs hardness 5–6, a fine-grained texture, and a dull to slightly waxy luster; individual crystals are usually too small to see.
Formation & geological history
Basalt forms when iron- and magnesium-rich lava cools at or near Earth’s surface; basaltic rocks occur from ancient to recent geological periods. The pebble’s rounded shape likely results from abrasion in a stream or on a beach.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building material; this small pebble has little commercial value beyond collecting or decoration.
Geological facts
Basalt is Earth’s most abundant volcanic rock and makes up much of the ocean floor.
Field identification & locations
A dark, fine-grained, dense pebble with no obvious large crystals is consistent with basalt, but the image lacks enough detail for a confident identification. Similar-looking dark pebbles can be other rocks or minerals; basalt is common worldwide, especially near volcanic regions and coastlines.
