sedimentary

Sandstone

Arenite (primarily SiO2)

Hardness: 6-7 on Mohs scale (depending on cementation); Color: Tan, brown, or olive-green; Luster: Dull/Earthy; Crystal structure: Clastic (composed of sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8

Hardness: 6-7 on Mohs scale (depending on cementation)
Color: Tan, brown, or olive-green
Luster: Dull/Earthy

Identified March 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral particles or rock fragments. This specimen appears to be a water-worn river pebble, likely dating from the Paleozoic to Cenozoic eras depending on local geography.

Uses & applications

Commonly used as a building material, paving stone, and in the manufacturing of glass and grindstones. In the petrologic industry, it acts as a primary reservoir for groundwater and petroleum.

Geological facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The famous Red Rocks Amphitheatre in Colorado is a massive natural sandstone formation.

Field identification & locations

Field identification is done by its gritty, abrasive texture (like sandpaper) and visible grains. It is ubiquitous globally, especially in dry environments and riverbeds. Collectors look for unique banding or fossil inclusions.