sedimentary

Sandstone

Arenite (Siliclastic sedimentary rock)

Hardness: 6-7 (Mohs scale); Color: Tan, brown, or gray; Luster: Dull (earthy); Crystal structure: Clastic (composed of mineral grains); Cleavage: None (fractures around grains); Specific gravity: 2.2-2.8

Hardness: 6-7 (Mohs scale)
Color: Tan, brown, or gray
Luster: Dull (earthy)

Identified January 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the accumulation and cementation of sand-sized mineral grains or rock fragments (0.0625 to 2 mm) under pressure. Typically found in deserts, riverbeds, and ocean basins. Geological age varies from Precambrian to Holocene.

Uses & applications

Extensively used as a building material, road base, and decorative stone. It is also used in glass manufacturing (if high silica) and as an abrasive in some industries.

Geological facts

Sandstone is often porous enough to act as a natural reservoir for groundwater, oil, and natural gas. Some sandstones, like Old Red Sandstone, are famous for preserving significant fossils from the Devonian period.

Field identification & locations

Identify in the field by its gritty texture (feels like sandpaper) and visible layers (bedding). It is commonly found in mountainous regions, canyons, and coastal cliffs. Collectors should look for unique cross-bedding or ripple marks.

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