sedimentary

Water-worn gray sandstone or quartzite pebble

Quartz-rich sandstone (possibly weakly metamorphosed quartzite), chiefly SiO₂

AI-generated identification · may be incorrect

Hardness approximately 6–7 Mohs; gray, tan, and iron-oxide brown coloration; dull to subtly sugary luster; rounded by abrasion. Quartz grains are visible, with no obvious cleavage and likely moderate-to-high density.

Identified September 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Most likely lithified quartz-rich sand later compacted and cemented, then rounded in a river or beach; if quartzite, it underwent later metamorphism. Exact geological age cannot be determined from the photograph.

Uses & applications

Commonly used as landscaping stone, aggregate, paving material, and decorative stone; attractive polished pieces may be sold as low-cost specimens.

Geological facts

The smooth oval shape is environmental rather than crystal-controlled, produced by prolonged transport and abrasion. Rust-colored patches indicate oxidation of iron-bearing minerals or cement.

Field identification & locations

Identify by gritty granular texture, abundant quartz, lack of strong foliation, and inability to scratch it with a steel nail if quartzite-like; acid reaction should be absent. Common worldwide in streambeds, beaches, and glacial deposits.