sedimentary

Red Sandstone

Arenite (Ferruginous Sandstone)

Hardness: 6-7 (on Mohs scale); Color: Reddish-brown to maroon due to iron oxide; Luster: Dull/Earthy; Crystal Structure: Clastic (grainy texture); Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6-7 (on Mohs scale)
Color: Reddish-brown to maroon due to iron oxide
Luster: Dull/Earthy

Identified May 7, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (on Mohs scale); Color: Reddish-brown to maroon due to iron oxide; Luster: Dull/Earthy; Crystal Structure: Clastic (grainy texture); Cleavage: None; Specific Gravity: 2.2-2.8

Formation & geological history

Formed through the accumulation and cementation of sand-sized grains, primarily quartz and feldspar, in desert or river environments. The red color indicates oxygen-rich conditions where hematite (iron oxide) acts as the cementing agent. Age varies globally from Precambrian to Cenozoic.

Uses & applications

Commonly used as a dimension stone in construction (flagstones, walling), architectural carvings, and sometimes ground down for industrial sand or as an abrasive.

Geological facts

Red sandstone is the primary rock found in famous geological formations like the Grand Canyon and the 'Red Rocks' of Sedona, Arizona. It often preserves sedimentary structures like cross-bedding from ancient sand dunes.

Field identification & locations

Identify in the field by its sandpaper-like feel and visible layering (stratification). It will not fizz with acid unless it has a calcitic cement. Found in ancient sedimentary basins worldwide.