sedimentary

Red Sandstone

Arenite (Ferruginous Sandstone)

Hardness: 6.5-7 (Mohs scale); Color: Red, reddish-brown, or orange due to iron oxide; Luster: Dull/Earthy; Crystal Structure: Clastic texture with sand-sized grains; Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6
Color: Red, reddish-brown, or orange due to iron oxide
Luster: Dull/Earthy

Identified May 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. The red color indicates formation in an oxygen-rich environment where iron minerals oxidized (rusted). Often associated with desert dunes, riverbeds, or floodplains from various geological eras.

Uses & applications

Widely used as a building material, decorative stone, for paving, and in the manufacturing of grindstones. Also used as an aquifer for groundwater and a reservoir for oil and gas.

Geological facts

The famous red rocks of Sedona, Arizona, and the 'Old Red Sandstone' of the British Isles are iconic examples. It has been used since ancient times for monuments, including parts of the Taj Mahal and the Red Fort in India.

Field identification & locations

Identify in the field by its gritty, sandpaper-like feel and visible grains. It is commonly found in sedimentary basins and arid regions. Collectors should look for unique cross-bedding patterns or fossil inclusions.