sedimentary

Sandstone (Ferruginous)

Arenite (SiO2 with Fe2O3 inclusions)

Hardness: 6-7 on Mohs scale; Color: Reddish-brown, tan, or orange due to iron oxide; Luster: Dull to earthy (sparkly surface indicates quartz grains); Crystal Structure: Granular/clastic; Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6-7 on Mohs scale
Color: Reddish-brown, tan, or orange due to iron oxide
Luster: Dull to earthy (sparkly surface indicates quartz grains)

Identified June 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral or rock grains. The reddish tint suggests formation in an oxygen-rich terrestrial environment where iron minerals oxidized (rusted) during lithification. Most common in desert or river delta deposits.

Uses & applications

Used widely in construction as a building stone (brownstone), paving material, and as an aquifer for groundwater or a reservoir for oil and gas. Fine specimens are used in landscaping and garden decor.

Geological facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The famous red rock formations in Sedona, Arizona and the 'wave' in Utah are composed of this type of ferruginous sandstone.

Field identification & locations

Identify by its gritty, sandpaper-like feel and visible grains. It can be found globally in sedimentary basins. Collectors should look for unique layering (cross-bedding) or fossil inclusions.

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