sedimentary

Sandstone (Ferruginous)

Arenite with Iron Oxide cement (primarily SiO2 with Fe2O3)

Hardness: 6-7 (Mohs scale); Color: Brownish-red to tan; Luster: Dull/Earthy; Crystal Structure: Clastic (grain-based); Cleavage: None (conchoidal fracture possible in grains); Specific Gravity: 2.2-2.8

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

Identified March 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments (clasts). The iron-rich coloring suggests oxidation in a terrestrial environment such as an ancient riverbed or desert. Geological age varies widely from Precambrian to Holocene.

Uses & applications

Commonly used in construction as a building stone or road base, as an abrasive in industry, or as an aquifer in geology due to its porosity.

Geological facts

Sandstone accounts for approximately 20% of all sedimentary rocks on Earth. The distinct red-brown color in specimens like this is caused by hematite or goethite acting as a mineral 'glue' or coating on the quartz grains.

Field identification & locations

Identify in the field by its gritty texture (feels like sandpaper) and visible layering if present. Commonly found in riverbeds, canyons, and coastal plateaus. For collectors, it represents a classic example of lithification.

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