sedimentary

Weathered river cobble, likely quartzite or sandstone

Indeterminate; probable quartz-rich sandstone/quartzite

AI-generated identification · may be incorrect

Rounded, fine-grained, tan-gray stone with dull earthy luster and iron-oxide staining; likely hardness 6–7 if quartzite, or 4–6 if sandstone. Massive with no visible cleavage; density approximately 2.5–2.7 g/cm³.

Identified August 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Rounded by transport in a stream, glacial deposit, or alluvial gravel; the original sedimentary rock may be Paleozoic or younger, but age cannot be determined from the image. Surface weathering produced the orange-brown coating.

Uses & applications

Commonly used as landscaping stone, garden edging, fill, and decorative cobble; generally little collector value unless it proves distinctive or fossiliferous.

Geological facts

The smooth shape records abrasion during transport, while rusty coloration commonly reflects oxidized iron minerals. A scratch test and fresh fracture are needed for confident identification.

Field identification & locations

Common in riverbeds, alluvial fans, glacial gravels, and field deposits. Quartzite resists scratching by a steel knife and shows sugary crystalline fracture; sandstone is usually more porous and may crumble or reveal visible grains.