sedimentary

Sandstone

Arenite (primarily SiO2)

Hardness: 6-7 (on Mohs scale); Color: tan, cream, or light brown; Luster: dull/earthy; Crystal structure: clastic (sand grains); Cleavage: none; Specific gravity: 2.2-2.8. Features a gritty texture like sandpaper.

Hardness: 6-7 (on Mohs scale)
Color: tan, cream, or light brown
Luster: dull/earthy

Identified January 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of mineral particles or rock fragments (clasts) that are sand-sized (0.0625 to 2 mm). These sediments typically deposit in riverbeds, deserts, or coastal environments. This specimen appears water-worn, likely from a fluvial or glacial environment.

Uses & applications

Extensively used as a building material, for paving stones, in glass manufacturing (if high silica content), and as a reservoir rock for oil and natural gas.

Geological facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The dark indentations on this specimen may be small vugs or 'clay galls' where softer material has weathered away. Some sandstones preserve fossils and ancient ripple marks from prehistoric shores.

Field identification & locations

Identify in the field by its gritty 'sandpaper' feel. Look for bedding layers or grain uniformity. It is commonly found in sedimentary basins and along riverbanks or beaches. Collectors value specimens with unique weathering patterns or mineral staining (iron oxide).