Sandstone (with differential weathering)

Physical Properties

Hardness: 6-7 Mohs; Color: Light grey to beige; Luster: Dull/Earthy; Structure: Clastic with concentric erosion patterns; Cleavage: None

Formation & Geological History

Formed from the accumulation and cementation of mineral particles (lithification) in high-energy aquatic environments. The concentric rings are caused by differential weathering of harder and softer layers, or potentially Liesegang rings (chemical precipitation).

Uses & Applications

Common industrial sand source, construction filler, decorative garden stone, and educational geological specimen.

Geological Facts

Sandstone makes up about 10-20% of all sedimentary rocks on Earth. The concentric pattern on this specific river-worn pebble showcases 'onion-skin' or spheroidal weathering, where layers peel away like an onion.

Field Identification & Locations

Identify in the field by its gritty texture (feels like sandpaper) and visible bedding planes. Commonly found in riverbeds, beaches, and canyons.

Identified on: 4/24/2026

Mode: Standard