sedimentary
Ferruginous Sandstone
Ferruginous Quartz-Arenite
Hardness: 6-7 (individual grains), Color: reddish-brown to dark tan, Luster: dull to earthy, Crystal structure: granular/clastic, Cleavage: none, Specific Gravity: 2.3-2.6
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Physical properties
Hardness: 6-7 (individual grains), Color: reddish-brown to dark tan, Luster: dull to earthy, Crystal structure: granular/clastic, Cleavage: none, Specific Gravity: 2.3-2.6
Formation & geological history
Formed via the accumulation of sand-sized mineral particles (mostly quartz) in high-energy environments like rivers or beaches, subsequently cemented by iron oxide minerals like hematite or goethite. Age ranges from modern to billions of years old.
Uses & applications
Used as a construction material, architectural stone, road aggregate, and as a source of iron ore in rare highly-concentrated cases. Often used in landscaping.
Geological facts
The red color is caused by the oxidation of iron minerals, essentially making the rock 'rusted.' This type of stone is responsible for the dramatic red vistas in places like Sedona, Arizona, and the Australian Outback.
Field identification & locations
Identify by its gritty, sandpaper-like texture and the way it may rub off reddish dust. Found globally in sedimentary basins. Collectors often look for examples with distinct cross-bedding or fossil inclusions.
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