sedimentary

Weathered sandstone or iron-rich sedimentary cobble

Quartz-rich sandstone, possibly ferruginous sandstone

AI-generated identification · may be incorrect

Brown to reddish-brown, dull earthy luster, visibly granular texture, and rounded weathered shape. Likely hardness about 6–7 due to quartz; no obvious cleavage or crystal faces, with moderate specific gravity around 2.3–2.7.

Identified September 2, 2026More sedimentary →

Explore Weathered sandstone or iron-rich sedimentary cobble in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed when sand-sized grains—mostly quartz, with iron-oxide cement—were compacted and lithified, then rounded by erosion and transport. Its precise geological age cannot be determined from the photograph.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally decorative material; this small cobble has little commercial value but may be a useful teaching or collection specimen.

Geological facts

The reddish-brown coloration typically comes from hematite or limonite coatings and cement. Surface rounding indicates transport by water, waves, or prolonged weathering.

Field identification & locations

Identify it by rubbing a fresh surface: visible sand grains and a gritty texture support sandstone; quartz-rich pieces resist scratching by a steel knife. Common in riverbeds, beaches, deserts, and sedimentary outcrops worldwide.