sedimentary

Rounded brown pebble

Likely iron-stained quartzite or chert; exact identification is uncertain from the photograph

AI-generated identification · may be incorrect

Hardness likely about 6.5–7 Mohs, opaque brown with a dull to slightly waxy luster and no obvious cleavage. Its smooth, rounded form reflects abrasion in a stream or gravel deposit; the visible line may be a natural fracture or seam.

Identified September 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably a durable siliceous cobble derived from weathered bedrock and rounded by water or sediment transport. Its original geological age cannot be determined visually; iron-oxide staining produced the brown color.

Uses & applications

Typically used as landscaping gravel, aggregate, or a hand specimen; it has little jewelry value unless it proves to be attractive chert or jasper. Common specimens are mainly of educational or personal interest.

Geological facts

Quartzite is recrystallized sandstone, whereas chert is microcrystalline quartz; both can look similar when weathered and rounded. A steel nail or knife should not easily scratch it, while quartz will scratch ordinary glass.

Field identification & locations

Common in streambeds, glacial deposits, beaches, and gravel pits worldwide. Test an inconspicuous spot for glass-scratching hardness and inspect a fresh chip for quartz-rich, glassy texture; laboratory testing is needed for certainty.