sedimentary

Sandstone

Arenite (primarily SiO2)

Hardness: 6-7 on Mohs scale; Color: Grey, tan, brown, or red; Luster: Dull or earthy; Crystal structure: Clastic (grains of sand); Specific gravity: 2.2-2.8

Hardness: 6-7 on Mohs scale
Color: Grey, tan, brown, or red
Luster: Dull or earthy

Identified March 18, 2026More sedimentary →

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Physical properties

Hardness: 6-7 on Mohs scale; Color: Grey, tan, brown, or red; Luster: Dull or earthy; Crystal structure: Clastic (grains of sand); Specific gravity: 2.2-2.8

Formation & geological history

Formed from the accumulation and cementation of sand-sized mineral grains or rock fragments (usually quartz or feldspar) over millions of years in environments like beaches, deserts, or river beds. This sample shows distinct bedding planes or weathering rinds.

Uses & applications

Widely used as a construction material for flagstones, paving, and building facades. Also used as a reservoir rock for oil, gas, and groundwater. Crushed sandstone is used in road bases.

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 sandstone layers.

Field identification & locations

Identify in the field by its 'gritty' feel (like sandpaper) and visible layers or bedding. It is common worldwide, particularly in basin regions. Collectors look for 'Picture Sandstone' or specimens with fossil inclusions.