sedimentary
Pebble (likely Siltstone or fine-grained Sandstone)
Sedimentary Clastic Rock
Hardness: 6-7 (Mohs); Color: Greyish-green with fine grains; Luster: Dull/Earthy; Crystal Structure: Clastic (non-crystalline); Cleavage: None; Specific Gravity: Approx. 2.6
- Hardness
- 6-7 (Mohs)
- Color
- Greyish-green with fine grains
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (Mohs); Color: Greyish-green with fine grains; Luster: Dull/Earthy; Crystal Structure: Clastic (non-crystalline); Cleavage: None; Specific Gravity: Approx. 2.6
Formation & geological history
Formed through the accumulation and lithification of fine-grained sediment (silt or sand) in low-energy environments like riverbeds or lake bottoms, followed by mechanical weathering and water erosion into a rounded shape.
Uses & applications
Commonly used as decorative garden stones, in construction aggregate, or as 'worry stones' due to smooth texture.
Geological facts
The smooth, oval shape is the result of 'abrasion'—thousands of years of being tumbled by water against other rocks in a river or coastal environment.
Field identification & locations
Identify by its smooth, water-worn texture and fine-grained consistency. Commonly found on beaches, riverbanks, and glacial till deposits. Use a magnifying glass to see individual sediment grains.
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