
sedimentary
Perforated beach pebble (likely sandstone or chert)
Indeterminate siliciclastic sedimentary rock; predominantly quartz (SiO₂), possibly calcareous cement
AI-generated identification · may be incorrectSmooth, water-worn brown pebble with matte to faintly silky luster and a natural rounded cavity/taphole; likely hardness about 5–7 Mohs, noncleaving, fine-grained, with variable porosity and specific gravity around 2.3–2.7.
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Physical properties
Smooth, water-worn brown pebble with matte to faintly silky luster and a natural rounded cavity/taphole; likely hardness about 5–7 Mohs, noncleaving, fine-grained, with variable porosity and specific gravity around 2.3–2.7.
Formation & geological history
Formed from lithified sand or silica-rich sediment, then rounded by abrasion in a river, beach, or surf zone; the cavity may reflect differential erosion around a softer inclusion or dissolved shell/clast. Exact geological age cannot be determined from the image.
Uses & applications
Primarily a decorative or collectible curiosity; similar stone is used as aggregate, landscaping material, and occasionally ornamental stone, but this individual has little commercial utility.
Geological facts
The hole appears naturally eroded rather than drilled, making it a “hag stone” or “witch stone,” a traditional folklore name for naturally holed pebbles.
Field identification & locations
Look for quartz grains or conchoidal fracture for identification; acid fizz would indicate carbonate cement or limestone. Common along rocky coasts and gravel bars worldwide.
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