Red Sandstone

Physical Properties

Hardness: 6-7 on Mohs scale; Color: reddish-brown to orange; Luster: dull/earthy; Crystal structure: clastic (primarily quartz grains); Cleavage: none; Specific gravity: 2.2-2.8.

Formation & Geological History

Formed through the accumulation and lithification of sand-sized mineral particles or rock fragments. The red color is due to the presence of iron oxide (hematite) which acts as a cementing agent. These often form in desert or fluvial environments and can date from billions of years to relatively recent geological eras.

Uses & Applications

Used widely in construction for building facades, paving, and decorative garden stones. Historically significant as a building material for temples, cathedrals, and monuments.

Geological Facts

Red sandstone is famous for creating the landscape of the American Southwest, including the Grand Canyon. The 'Old Red Sandstone' is a world-renowned suite of rocks in the UK that helped geologists first understand the Devonian period.

Field Identification & Locations

Identify by its gritty, sandpaper-like feel and visible sand grains. It is commonly found in sedimentary basins and arid regions. Collectors should look for unique cross-bedding layers or trace fossils within the specimen.

Identified on: 5/5/2026

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