sedimentary

Jasper-rich ironstone

Microcrystalline quartz (SiO₂) with hematite/goethite and iron oxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque reddish-brown with black-gray patches, earthy to dull luster, dense and fine-grained, with no visible cleavage. The irregular surface and coloration suggest a natural rough or lightly weathered specimen.

Identified September 9, 2026More sedimentary →

Explore Jasper-rich ironstone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed when silica-rich fluids cemented or replaced iron-bearing sediments, concentrating hematite and related oxides; age depends on locality, commonly Precambrian to younger. Such material occurs in ancient iron formations, weathering zones, and hydrothermal settings.

Uses & applications

Used as ornamental stone, cabochons, carvings, tumbled material, and lapidary rough; iron-rich varieties may have limited industrial significance. Common specimens generally have modest collector value.

Geological facts

The red color is mainly from hematite or finely dispersed iron oxides, while black areas may contain magnetite, manganese oxides, or darker jasper. A concealed fresh surface often shows sharper red-black patterning than the weathered exterior.

Field identification & locations

Commonly found in Australia, Brazil, India, South Africa, and the western United States. Identify by its very fine texture, opaque red-black coloration, heft, and ability to scratch glass; acid produces no meaningful reaction.