sedimentary

Weathered jasper-rich ironstone

Siliceous ironstone, likely jasper/chert with hematite and goethite

AI-generated identification · may be incorrect

Hardness about 6.5–7 for the silica-rich portions; massive, fine-grained, opaque, with reddish-brown, ochre, gray, and greenish surfaces, earthy to dull luster, and no obvious cleavage. The cavities and dark metallic-looking patches likely reflect weathering and iron-oxide alteration.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably formed as silica-rich sediment or chert later impregnated and stained by iron oxides during groundwater alteration; its exact geological age cannot be determined from the photograph. Weathering produced the rounded shape and hollow cavities.

Uses & applications

Used as a lapidary, display, or teaching specimen; attractive pieces may be cut and polished, though this example appears mainly suitable for collecting. Ironstone can locally be an iron ore, but this specimen is unlikely to have economic ore value.

Geological facts

The red and yellow colors commonly come from hematite and goethite, while green tones may reflect chlorite or other secondary minerals. A fresh broken surface would be more diagnostic than the weathered exterior.

Field identification & locations

Common in iron-rich sedimentary terrains worldwide, including Australia, India, Brazil, and North America. Test a fresh edge for glassy conchoidal fracture and hardness: silica should scratch ordinary glass, whereas softer earthy coatings may not.