igneous
Rounded river pebble, likely basalt or dark volcanic rock
Probably fine-grained basalt; exact identification requires testing
AI-generated identification · may be incorrectDark olive-gray, smooth and water-worn, with a dull to slightly waxy luster and faint pale veins or weathering marks. Likely hardness about 5–6 Mohs, massive (non-crystalline to fine-crystalline), with no visible cleavage; density commonly 2.8–3.1 g/cm³.
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Physical properties
Dark olive-gray, smooth and water-worn, with a dull to slightly waxy luster and faint pale veins or weathering marks. Likely hardness about 5–6 Mohs, massive (non-crystalline to fine-crystalline), with no visible cleavage; density commonly 2.8–3.1 g/cm³.
Formation & geological history
Most likely a basaltic volcanic fragment transported and rounded by flowing water or shoreline abrasion. Basalt can range from Precambrian to modern in age, depending on its source.
Uses & applications
Primarily a decorative or educational specimen; similar pebbles are used in landscaping, crafts, aquaria, and polished-stone collections, but this example has little commercial value.
Geological facts
Its rounded shape records prolonged abrasion during transport. The pale curved markings may be mineral veins, surface weathering, or light-colored inclusions rather than fossils.
Field identification & locations
Common in riverbeds, beaches, and glacial deposits worldwide, especially near volcanic or mafic bedrock. A streak test, magnet test, fresh-edge inspection, and density measurement would help distinguish basalt from greenstone, chert, or serpentine.
