sedimentary
Red Sandstone
Clastic sedimentary rock (primarily SiO2 with Fe2O3)
Hardness: 6-7 (Mohs scale), Color: Reddish-brown to orange (due to iron oxide), Luster: Dull/Earthy, Crystal Structure: Granular/Clastic, Cleavage: None/Massive, Specific Gravity: 2.2 - 2.8
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Reddish-brown to orange (due to iron oxide), Luster: Dull/Earthy, Crystal Structure: Granular/Clastic, Cleavage: None/Massive, 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 formation in an oxygen-rich environment (aerobic), often in arid desert or continental river settings. These can range from Precambrian to Holocene in age.
Uses & applications
Widely used in the construction industry as a building stone (dimension stone), masonry, and for decorative paving. Red sandstone is also used as a reservoir rock for oil and natural gas.
Geological facts
Famous for creating the iconic landscapes of the American Southwest, such as the Grand Canyon and Antelope Canyon. The red color is effectively 'rust'—a thin coating of hematite on the quartz grains.
Field identification & locations
Identify by its gritty, sandpaper-like texture and its visible layers (bedding planes). It is commonly found in sedimentary basins and arid regions globally. Collectors should look for unique cross-bedding patterns or fossil inclusions.
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