sedimentary

Brown Pebble (River Rock)

Indeterminate (Likely Silicon Dioxide / Quartz-rich)

AI-generated identification · may be incorrect

Hardness: ~7 (Mohs), Color: Earthy brown to reddish-brown, Luster: Dull to matte (sub-vitreous if wet), Crystal Structure: Microcrystalline (Cryptocrystalline), Cleavage: None/Conchoidal fracture

Identified June 27, 2026More sedimentary →

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Physical properties

Hardness: ~7 (Mohs), Color: Earthy brown to reddish-brown, Luster: Dull to matte (sub-vitreous if wet), Crystal Structure: Microcrystalline (Cryptocrystalline), Cleavage: None/Conchoidal fracture

Formation & geological history

Formed through the erosion and weathering of larger rock formations, transported by water (rivers, streams, or glacial melt) which rounds the edges over centuries. Likely composed of chert, jasper, or weathered quartz.

Uses & applications

Landscaping, decorative garden mulch, industrial abrasives when crushed, or historical use as primitive tools (celt/scrapers).

Geological facts

The smooth, rounded shape is a result of fluvial abrasion, where rocks tumble together in running water. They are some of the most common geological finds worldwide.

Field identification & locations

Identify by its smooth, water-worn texture and lack of sharp edges. Commonly found in riverbeds, floodplains, and gravel pits. Collectors often look for unique colors or banding within these common shapes.