sedimentary

Sandstone (Ferruginous)

Clastic Sedimentary Rock (SiO2 with FeO/Fe2O3)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs scale); Color: Brownish-red to tan; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific gravity: 2.2–2.8

Hardness: 6-7 (Mohs scale)
Color: Brownish-red to tan
Luster: Dull/Earthy

Identified April 6, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs scale); Color: Brownish-red to tan; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific gravity: 2.2–2.8

Formation & geological history

Formed from the accumulation and cementation of sand-sized mineral grains or rock fragments. The reddish-brown color indicates iron-oxide cementation (limonite or hematite). Typically formed in river beds, beaches, or desert dunes over millions of years.

Uses & applications

Commonly used in construction, architectural stone, grindstones, and as a reservoir rock for water and petroleum.

Geological facts

Sandstone makes up about 10-20% of all sedimentary rocks on Earth. The 'red' sandstones of the American Southwest owe their color to the same iron oxidation process seen in this specimen.

Field identification & locations

Identify by its gritty texture (feels like sandpaper) and visible sand grains. Found globally in basins and near continental margins. For collectors, look for cross-bedding or fossil inclusions.