sedimentary

Weathered sandstone pebble

Quartz-rich sandstone, likely ferruginous or arkosic

AI-generated identification · may be incorrect

Tan to reddish-brown, dull earthy luster, visibly granular and highly porous with weathering pits; composed mainly of quartz grains with feldspar, clay, and iron oxides. Typical hardness is about 6–7 for individual quartz grains, but the rock is friable; no obvious cleavage or crystals are visible.

Identified September 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand was deposited, compacted, and cemented, probably in a river, beach, or desert environment. Its precise geological age cannot be determined from the photograph; surface oxidation and abrasion produced the rounded shape.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally decorative material; this small specimen has little commercial or jewelry value.

Geological facts

The orange-brown coloration commonly comes from hematite or goethite coatings between grains. The cavities may reflect weak cement, weathering, or dissolution of less-resistant grains.

Field identification & locations

Identify sandstone by its gritty texture, visible sand-sized grains, layered or porous appearance, and ability to scratch glass if quartz-rich; dilute acid usually produces no reaction unless carbonate cement is present. Common worldwide in sedimentary basins and stream gravels.