sedimentary
Red Sandstone Pebble
Arenite (primarily Quartz SiO2 with Hematite Fe2O3 staining)
Hardness: 6-7 (individual grains); Color: Reddish-brown to terracotta; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 (individual grains)
- Color
- Reddish-brown to terracotta
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (individual grains); Color: Reddish-brown to terracotta; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. The red color indicates oxidation of iron-bearing minerals (hematite) in terrestrial environments. These can date from the Paleozoic to Cenozoic eras.
Uses & applications
Used primarily in landscaping, construction (as aggregate), and occasionally as a decorative architectural stone or for making sharpening stones.
Geological facts
Famous red sandstone formations include the 'Red Rocks' of Colorado and the 'Old Red Sandstone' of Northern Europe. The red color is often a sign of 'red beds,' which indicate the sediment was deposited in an oxygen-rich, dry environment.
Field identification & locations
Identify by its gritty texture (like sandpaper) and reddish rub-off. Found globally in riverbeds, deserts, and coastal areas. Collectors look for unique shapes weathered by water erosion.
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