Sandstone

Physical Properties

Hardness: 6-7 (on Mohs scale if quartz-rich); Color: reddish-brown, tan, or gray; Luster: matte/dull; Crystal structure: granular texture; Cleavage: none (breaks across grains); Specific gravity: 2.2-2.8

Formation & Geological History

Formed through the accumulation and cementation of mineral particles or rock fragments (clasts) the size of sand. These typically deposit in river beds, deserts, or marine environments. This specimen shows iron-oxide staining, giving it the reddish hue common in terrestrial deposits.

Uses & Applications

Used widely in construction as a building stone, for making grindstones, as a source for silica in glass manufacturing, and as a reservoir rock for oil and natural gas.

Geological Facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The famous red rocks of the Grand Canyon and Petra in Jordan are primarily composed of various layers of sandstone.

Field Identification & Locations

Identify in the field by its gritty, sandpaper-like feel. It can often be scratched with a steel blade if the cement is weak. Look for bedding planes or layering within larger outcrops.

Identified on: 4/15/2026

Mode: Standard