sedimentary

Brown quartz-rich pebble (likely chert or weathered quartzite)

Quartz (SiO₂), possibly microcrystalline quartz/chert or quartzite

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown to gray-brown, dull to weakly glassy luster, granular-looking texture, and no obvious cleavage. The rounded shape indicates natural water abrasion; exact identification is limited without a fresh surface or tests.

Identified August 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed as a silica-rich sedimentary rock (chert) or metamorphosed sandstone (quartzite), then weathered and transported in a stream or gravel deposit. Its geological age cannot be determined from the photograph.

Uses & applications

Common pieces are used as landscaping gravel, aggregate, flint-like tool material, or inexpensive collected specimens; attractive polished examples may be sold as decorative stones.

Geological facts

Quartz-rich rocks commonly resist weathering and become rounded pebbles. A streak, hardness, and acid test would help distinguish chert from quartzite and other brown rocks.

Field identification & locations

Look for a scratch on ordinary glass: quartz-rich material should scratch it; chert has a smooth waxy fracture, while quartzite shows visible interlocking grains. Common worldwide in river gravels and sedimentary or metamorphic terrains.