sedimentary
Sandstone (with Iron Staining)
Arenite (SiO2 predominantly)
Hardness: 6-7 (Mohs scale), Color: Tan, brown, or reddish-brown due to iron oxide, Luster: Dull or earthy, Crystal structure: Granular/clastic, Cleavage: None (conchoidal fracture when fine-grained)
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Tan, brown, or reddish-brown due to iron oxide, Luster: Dull or earthy, Crystal structure: Granular/clastic, Cleavage: None (conchoidal fracture when fine-grained)
Formation & geological history
Formed over millions of years through the accumulation and cementation of sand-sized mineral particles or rock fragments, typically in riverbeds, deserts, or coastal environments. Potential geological age ranges from Precambrian to Holocene.
Uses & applications
Commonly used as a building material, in paving, as a source of silica for glass making, or as an ornamental stone in landscaping.
Geological facts
Sandstone is one of the most common sedimentary rocks on Earth. It often preserves fossils and ripple marks that reveal ancient environmental conditions. Red sandstones owe their color to hematite or goethite coatings on sand grains.
Field identification & locations
Identify in the field by its gritty, sandpaper-like texture and visible layered bedding. It is found globally in sedimentary basins. Collectors often look for colorful banding or fossil inclusions.
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