sedimentary

River Pebble (Siltstone / Quartzite)

Sedimentary Clast (Siliceous Siltstone / Quartzite pebble)

AI-generated identification · may be incorrect

Hardness: 6-7 on Mohs scale (if siliceous) or 3-5 (if clay-rich); Color: dull light gray to greenish-gray; Luster: dull to earthy; Texture: microcrystalline or fine clastic, smoothly rounded by water abrasion.

Hardness: 6-7 on Mohs scale (if siliceous) or 3-5 (if clay-rich)
Color: dull light gray to greenish-gray
Luster: dull to earthy

Identified November 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through mechanical weathering and alluvial or fluvial transport. Originally deposited in a low-to-medium energy sedimentary environment, later eroded, transported, and rounded by flowing water in a stream, river, or shoreline.

Uses & applications

Commonly used as aggregate in construction, landscaping gravel, pathway paving, and decorative garden ground cover.

Geological facts

The rounded shape of pebbles is created through fluvial attrition, where moving water rolls rock fragments against one another, grinding away sharp edges over decades or centuries.

Field identification & locations

Identified by its small, smooth, sub-rounded to rounded shape, uniform dull gray tone, and lack of visible coarse grains. Abundantly found in riverbeds, beaches, and glacial gravel deposits worldwide.