sedimentary

Iron-stained quartz-rich rock (likely ironstone or ferruginous quartz)

Ferruginous quartz-rich rock; exact mineralogy cannot be determined from the photograph

AI-generated identification · may be incorrect

Rough, irregular, brown-orange surface with darker gray-brown areas, consistent with iron-oxide staining. Hardness and crystal structure cannot be confirmed visually; likely quartz-rich (Mohs 7) with iron oxides such as goethite or hematite.

Identified September 28, 2026More sedimentary →

Explore Iron-stained quartz-rich rock (likely ironstone or ferruginous quartz) in the encyclopedia →

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Physical properties

Formation & geological history

May have formed when iron-rich groundwater precipitated oxides around or within silica-rich material. Geological age and precise formation setting cannot be determined from the image.

Uses & applications

Small specimens are mainly kept for collecting or teaching; ironstone may be used locally as building stone or iron ore when sufficiently iron-rich.

Geological facts

Brown, rusty coloration commonly results from iron oxides and hydroxides coating or cementing grains.

Field identification & locations

Look for a hard, gritty or glassy fracture and rusty streaks; a streak test, magnet test, or closer examination can help distinguish ironstone from other rocks. Iron-rich rocks occur worldwide.