Sandstone

Physical Properties

Hardness: 6-7 (individual grains); Color: Tan, brown, or earthy yellow; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.0-2.6

Formation & Geological History

Formed through the accumulation and cementation of mineral particles or rock fragments (clastic) of silica and/or feldspar. This specimen appears to be a river-worn pebble, likely millions of years old, shaped by fluvial transport.

Uses & Applications

Used primarily in construction (building stone, flagstone), as an abrasive material, and as a reservoir rock for oil and natural gas.

Geological Facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. Notable formations include the red rocks of the Grand Canyon and the Nabataean architecture in Petra.

Field Identification & Locations

Identify in the field by its 'sandpaper' feel and visible grains. Often found in riverbeds, deserts, and coastal areas. Collectors look for unique banding or fossils within the layers.

Identified on: 4/13/2026

Mode: Standard