sedimentary

Red jasper (likely iron-rich chert)

Microcrystalline quartz (SiO₂) colored by hematite/goethite

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, opaque red to brown with tan weathering, and dull to waxy luster. It has a cryptocrystalline quartz structure, no obvious cleavage, and specific gravity around 2.6; the photographed piece may include a softer, porous host rock.

Identified August 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich sediment or volcanic material is replaced or cemented by microcrystalline quartz, with iron oxides producing the red color. It can form in Precambrian to much younger environments, commonly in iron-rich sedimentary beds and hydrothermal settings.

Uses & applications

Used as ornamental stone, cabochons, beads, carvings, tumbled stone, and aggregate; attractive specimens have modest lapidary value.

Geological facts

Jasper is a variety of chert distinguished mainly by its opacity and abundant impurities. Red coloration commonly results from finely disseminated hematite rather than the quartz itself.

Field identification & locations

Identify it by its opaque red coloration, waxy surface, very fine texture, and resistance to scratching; it should scratch glass but not be scratched by a steel knife. Common sources include India, Brazil, Madagascar, Australia, and the western United States.