sedimentary
Sandstone (Ferruginous)
Arenite (Fe2O3 dominant staining)
Hardness: 6-7 (Mohs scale), Color: Reddish-brown to tan, Luster: Dull (earthy), Crystal Structure: Granular/clastic grains, Cleavage: None (fractures roughly), Specific Gravity: 2.2-2.8
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Reddish-brown to tan, Luster: Dull (earthy), Crystal Structure: Granular/clastic grains, Cleavage: None (fractures roughly), Specific Gravity: 2.2-2.8
Formation & geological history
Formed from the accumulation and cementation of sand-sized grains, typically quartz. The reddish color indicates the presence of iron oxide (hematite) cement. This specimen is a water-rounded river stone or cobble, likely of Paleozoic or Mesozoic age.
Uses & applications
Commonly used as building stone, pavers, and decorative landscaping. High-quality sandstone is also used for glass manufacturing or as an abrasive.
Geological facts
The distinct bands or 'rings' seen on specimens like this are often 'Liesegang rings', which form due to the rhythmic precipitation of minerals (usually iron) from groundwater saturated with chemicals.
Field identification & locations
Identify in the field by its gritty, sandpaper-like texture and visible sedimentary layering. It is ubiquitous in riverbeds and arid desert environments. Collectors look for unique banding or patterns caused by iron staining.
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