sedimentary

Rounded quartz-rich river pebble

Feldspathic quartz sandstone or quartzite pebble (exact identification requires testing)

AI-generated identification · may be incorrect

Fine-grained, cream to pale yellow, dull-to-slightly-satin luster, smoothly water-worn, with no visible crystals or cleavage. Likely hardness about 6–7 Mohs and specific gravity around 2.6; surface staining may be iron oxide.

Identified August 20, 2026More sedimentary →

Explore Rounded quartz-rich river pebble in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed from cemented quartz-rich sand, or metamorphosed sandstone if it is quartzite, then rounded by prolonged stream or beach abrasion. The rock’s depositional age cannot be determined from the photograph.

Uses & applications

Primarily a decorative, landscaping, craft, or teaching specimen; not typically valuable for jewelry or construction because of its small size and uncertain composition.

Geological facts

Its unusually smooth, egg-like shape indicates transport in moving water or surf. A glassy scratch test and resistance to a steel knife would support quartzite or quartz-rich sandstone.

Field identification & locations

Common in riverbeds, beaches, and glacial deposits. Examine a fresh chip with a loupe: quartz grains and gritty texture suggest sandstone, while a fused sugary texture suggests quartzite; dilute acid should produce no fizz.