sedimentary

Weathered iron-rich sandstone or ferruginous quartzite

Ferruginous sandstone; chiefly quartz (SiO₂) with iron oxides/hydroxides

AI-generated identification · may be incorrect

Hardness typically 6–7 if quartz-rich; brown, ochre, gray, and black; dull to earthy or weakly glassy luster. Grainy, massive texture with iron-stained fractures; cleavage absent and specific gravity roughly 2.5–2.8.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely siliciclastic sediment cemented by silica and iron minerals, then weathered and naturally rounded; age cannot be determined from the photograph. Hematite, goethite, or limonite produces the rusty coloration.

Uses & applications

Used locally as building or decorative stone and occasionally as iron-ore material; attractive pieces may be collected, but it is generally not a gemstone.

Geological facts

The dark surface may reflect manganese or iron-oxide coatings rather than a separate rock type. A white streak, visible sand grains, and lack of reaction to dilute hydrochloric acid support sandstone rather than carbonate rock.

Field identification & locations

Common in iron-rich sedimentary terrains worldwide, including parts of North America, Australia, India, and Africa. Test with a steel nail, inspect grain size with a loupe, and use streak color to distinguish hematite (red-brown) from goethite/limonite (yellow-brown).