sedimentary
Weathered Sandstone with Algae Growth
Arenite
Hardness: 6-7 (Mohs scale), Color: tan, brownish-red with green biological staining, Luster: Dull/Earthy, Crystal Structure: Granular/Clastic, Cleavage: None
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Physical properties
Hardness: 6-7 (Mohs scale), Color: tan, brownish-red with green biological staining, Luster: Dull/Earthy, Crystal Structure: Granular/Clastic, Cleavage: None
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral particles or rock fragments, typically within riverbeds, deserts, or marine environments over millions of years.
Uses & applications
Used widely in construction for building stone, aggregate for concrete, and pavement. In geological collecting, it is often studied for its porosity and potential as an oil/gas reservoir rock.
Geological facts
Sandstone makes up about 20% to 25% of all sedimentary rocks on Earth. The visible green patches on this specimen are likely lichen or algae, which contribute to biological weathering.
Field identification & locations
Identify in the field by its gritty texture (like sandpaper) and distinct bedding planes. Commonly found in canyons, river basins, and areas with exposed sedimentary strata.
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