sedimentary

Weathered sandstone or iron-stained quartz-rich river cobble

Quartz-rich sandstone; predominantly SiO₂ with iron-oxide staining

AI-generated identification · may be incorrect

Tan, granular, and dull-to-earthy in luster, with an irregular weathered surface; likely Mohs hardness about 6–7 for quartz grains, though cement and porosity vary. No visible crystal faces or cleavage; the dark lower portion may be iron/manganese staining or a different attached lithology.

Identified August 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably a naturally weathered and stream-rounded fragment eroded from local bedrock and transported in the river. Its depositional age cannot be determined from the photograph; sandstone commonly forms when sand is compacted and cemented in ancient rivers, beaches, or deserts.

Uses & applications

Usually a common geological collectible or teaching specimen, with little commercial value; sandstone is widely used as building stone, paving, and aggregate when sound.

Geological facts

The image is not detailed enough for confident species-level identification, and it could also be a weathered quartzite or iron-rich rock. A fresh broken surface and a hand lens would reveal whether grains are distinct (sandstone) or fused (quartzite).

Field identification & locations

Common in streambeds worldwide; identify by visible sand grains, gritty texture, and lack of strong cleavage. Test with a steel knife and dilute acid only if appropriate; iron staining produces yellow-brown to reddish colors.