Red Sandstone

Physical Properties

Hardness: 6-7 Mohs; Color: reddish-brown to rust due to iron oxide; Luster: matte/dull; Crystal structure: granular clastic texture; Cleavage: none (fractures along grain boundaries); Specific gravity: 2.2-2.8

Formation & Geological History

Formed from the accumulation and cementation of sand-sized grains, primarily quartz and feldspar, in desert or river environments. The red hue comes from hematite or goethite precipitation during diagenesis. Locations range from Paleozoic to Mesozoic ages.

Uses & Applications

Extensively used in construction for building facades, paving stones, and masonry. Used historically for monuments and as a source of high-purity silica for glassmaking in some varieties.

Geological Facts

Red sandstone is famous for creating the stunning landscapes of the American Southwest, such as the Grand Canyon and Zion National Park. It is often referred to as 'Old Red Sandstone' in European geology.

Field Identification & Locations

Identify in the field by its gritty, sandpaper-like feel and visible layering (bedding). It is commonly found in dried-up riverbeds, canyons, and desert regions globally. It does not fizz with acid unless it has a calcitic cement.

Identified on: 5/3/2026

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