sedimentary
Banded Pebble (Banded Argillite / Siltstone)
Laminated mudstone / argillite (predominantly SiO2 and clay minerals)
AI-generated identification · may be incorrectHardness 3.5-6 on the Mohs scale, with a dull to sub-waxy luster, fine-grained clastic texture, and distinct rhythmic dark gray and light gray bands.
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Physical properties
Hardness 3.5-6 on the Mohs scale, with a dull to sub-waxy luster, fine-grained clastic texture, and distinct rhythmic dark gray and light gray bands.
Formation & geological history
Formed by quiet-water deposition of alternating fine mud and silt layers in lacustrine or marine basins, subsequently compacted, cemented, and rounded by fluvial erosion.
Uses & applications
Commonly collected as wishing stones or decorative garden and aquarium gravel; occasionally tumbled or carved.
Geological facts
Pebbles with continuous unbroken white or contrasting bands encircling them are traditionally termed 'wishing stones' or 'lucky stones' in folklore.
Field identification & locations
Easily identified by fine alternating parallel laminae across a rounded, water-smoothed river or beach cobble. Found globally along riverbeds, lakeshores, and coastal beaches.
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