igneous
Polished dark river pebble
Indeterminate; likely basalt or fine-grained mafic rock
AI-generated identification · may be incorrectDark gray-brown, smooth and rounded with a dull to faintly waxy luster; fine-grained and massive, with no visible crystals or cleavage. Estimated Mohs hardness 5–6 and specific gravity roughly 2.8–3.1.
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Physical properties
Dark gray-brown, smooth and rounded with a dull to faintly waxy luster; fine-grained and massive, with no visible crystals or cleavage. Estimated Mohs hardness 5–6 and specific gravity roughly 2.8–3.1.
Formation & geological history
Probably an alluvial pebble naturally rounded by stream abrasion, possibly further smoothed or polished; basaltic rocks commonly formed from Cenozoic or older volcanic lava.
Uses & applications
Primarily a decorative, craft, or collection specimen; similar material is used as landscaping stone, aggregate, and occasionally in jewelry or worry stones. Value is usually minimal.
Geological facts
The small pale specks may be weathering products, feldspar, or trapped sediment, but the image cannot establish composition confidently.
Field identification & locations
Test for a glassy scratch with a steel file or knife, check for weak magnetism, and inspect a fresh surface for tiny plagioclase crystals; basalt is typically dense and nonporous. Common sources include volcanic terrains and streams worldwide.
