sedimentary

Sandstone

Arenite (composed primarily of SiO2)

Hardness: 6-7 on Mohs scale; Color: Tan, brown, or grey (often displaying weathering rinds); Luster: Dull or earthy; Crystal structure: Clastic (grain-based); Cleavage: None (breaks across grains); Specific Gravity: 2.2-2.8

Hardness: 6-7 on Mohs scale
Color: Tan, brown, or grey (often displaying weathering rinds)
Luster: Dull or earthy

Identified March 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of mineral particles or rock fragments of sand size (0.0625 to 2 mm). Typically originates in riverbeds, deserts, or marine environments. The specimen shown appears to be a water-worn or weathered cobble embedded in a secondary matrix.

Uses & applications

Commonly used as a building material, paving stone, and in the production of glass. It also serves as an important reservoir rock for groundwater and petroleum.

Geological facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. Famous structures like Petra in Jordan and the 'Red Rocks' of the American Southwest are composed of this material. The visible 'crust' on the specimen in the image is likely a weathering rind or caliche deposit.

Field identification & locations

Identify in the field by its gritty, sandpaper-like texture and visible sand grains. It is ubiquitous in sedimentary basins worldwide. Look for bedding planes or cross-bedding features in larger outcrops.