sedimentary
Pebble
Lithic fragment / Rounded rock fragment
Hardness varies depending on lithology (commonly 6-7 on Mohs scale if quartz-rich), greyish to brownish color, dull to sub-vitreous luster, amorphous to cryptocrystalline structure, no cleavage, specific gravity ranges around 2.6-2.7.
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Physical properties
Hardness varies depending on lithology (commonly 6-7 on Mohs scale if quartz-rich), greyish to brownish color, dull to sub-vitreous luster, amorphous to cryptocrystalline structure, no cleavage, specific gravity ranges around 2.6-2.7.
Formation & geological history
Formed through mechanical weathering and erosion of parent rocks, followed by the transport and rounding of rock fragments via water in rivers, streams, or wave action on beaches over geological timescales.
Uses & applications
Used in landscaping, decorative ground cover, concrete aggregate, and pathway construction.
Geological facts
Pebbles are officially classified by their grain size in the Wentworth scale, measuring between 4 and 64 millimeters in diameter.
Field identification & locations
Found abundantly in riverbeds, glacial tills, beaches, and alluvial fans worldwide. Identified by its small size and smooth, rounded shape resulting from abrasion.
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