sedimentary or metamorphic

Worn quartz-rich pebble, likely chert or quartzite

Microcrystalline quartz (SiO₂), possibly quartzite

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; gray-brown with a translucent tan, weathered outer zone, dull to waxy luster, and no obvious cleavage. The rounded shape and surface abrasion indicate water transport; exact identification is limited without a fresh break or tests.

Identified August 10, 2026More sedimentary or metamorphic →

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Physical properties

Formation & geological history

Likely formed as silica-rich sediment that lithified into chert, or as quartz sandstone recrystallized into quartzite; the specimen was later weathered and stream-worn. Its geological age cannot be determined from the image.

Uses & applications

Quartz-rich pebbles are used as aggregate, landscaping stone, and occasionally lapidary material; attractive pieces may be polished, but this example appears mainly collectible as a natural find.

Geological facts

A steel file should not readily scratch it, while quartz or a glass plate may scratch it; a fresh fracture in chert is typically conchoidal, whereas quartzite appears granular. A streak test is usually white.

Field identification & locations

Common in streambeds, gravel deposits, and glacial sediments worldwide, especially near quartz-bearing rocks. Acid reaction would be absent, helping distinguish it from limestone.