sedimentary

Sandstone

Arenite (primarily SiO2)

Hardness: 6-7 (Mohs scale); Color: Tan, brownish-yellow; Luster: Dull, earthy; Crystal structure: Clastic (composed of sand-sized grains); Cleavage: None; Specific gravity: 2.2–2.8

Hardness: 6-7 (Mohs scale)
Color: Tan, brownish-yellow
Luster: Dull, earthy

Identified February 18, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs scale); Color: Tan, brownish-yellow; Luster: Dull, earthy; Crystal structure: Clastic (composed of sand-sized grains); Cleavage: None; Specific gravity: 2.2–2.8

Formation & geological history

Formed through the accumulation and cementation of mineral particles or rock fragments (clasts). Common in desert, river, and coastal depositional environments. Rock ages can range from Pre-Cambrian to Holocene.

Uses & applications

Predominantly used as a building material, paving stones, and for ornamental work. It is also an important reservoir rock for groundwater and oil/gas.

Geological facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. Famous landmarks like the Grand Canyon and Petra in Jordan are carved from or composed of massive sandstone layers.

Field identification & locations

Identify by its 'gritty' feel (like sandpaper) and visible sand grains. Commonly found in riverbeds, cliffs, and deserts. Test with a drop of vinegar; if it fizzes slightly, it may have a calcite cement.