sedimentary

Iron-rich sandstone or ferruginous quartzite

Quartz-rich sandstone cemented by iron oxides; possibly weakly metamorphosed quartzite

AI-generated identification · may be incorrect

Hardness about 6–7; brown, rusty red, and tan granular surface with scattered white quartz grains; earthy to slightly glassy luster, no obvious cleavage, and likely moderate-to-high density. The rounded shape appears weathered or tumbled.

Identified September 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely deposited as sand, then cemented by silica and iron oxides; if metamorphosed, compaction and heating recrystallized it into quartzite. Exact age and locality cannot be determined from the photograph.

Uses & applications

Commonly used as building or paving stone and occasionally as decorative rock; generally little jewelry value unless unusually attractive or strongly mineralized.

Geological facts

Its rusty color comes mainly from hematite and/or goethite coatings between quartz grains. A steel scratch test and streak test can help distinguish sandstone from quartzite and identify iron staining.

Field identification & locations

Look for visible sand grains, quartz-rich composition, and reddish-brown iron staining; sandstone usually breaks around grains, whereas quartzite fractures through them. Common in sedimentary basins and iron-rich weathering zones worldwide.