sedimentary

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Hardness: 6-7 (Mohs scale); Color: Tan, yellow, or rusty orange (due to iron oxide); Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None/Grainy fracture; Specific gravity: 2.2 - 2.8

Hardness: 6-7 (Mohs scale)
Color: Tan, yellow, or rusty orange (due to iron oxide)
Luster: Dull/Earthy

Identified April 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation, compaction, and cementation of sand-sized mineral particles or rock fragments. Usually deposited in desert, river, or coastal environments. This specimen shows iron staining, suggesting exposure to oxygenated groundwater during or after lithification.

Uses & applications

Commonly used as a building material, paving stone, and in the manufacturing of glass. In the collection world, it is often used for landscape gardening or as a type specimen for clastic sedimentary rocks.

Geological facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The 'red rocks' of the American Southwest owe their color to the same iron oxide minerals visible in this specimen.

Field identification & locations

Identify by its gritty texture (feels like sandpaper) and visible layers of sand grains. Commonly found in basins or former seabed areas. Collectors should look for distinct bedding planes or fossils occasionally trapped within.

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