sedimentary

Red jasper (probable iron-rich chert)

Jasper, microcrystalline quartz (SiO₂) colored chiefly by hematite/goethite

AI-generated identification · may be incorrect

Opaque brick-red to brown, earthy-to-waxy luster, fine-grained and typically massive with no visible cleavage; Mohs hardness about 6.5–7, specific gravity roughly 2.5–2.7. The specimen appears rough and naturally fractured, with darker iron-rich patches.

Identified September 3, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich sediment or volcanic material is replaced and cemented by microcrystalline quartz, with iron oxides producing the red color; deposits range from Precambrian to younger ages. Common in hydrothermal, volcanic, and sedimentary environments.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and lapidary work; crushed jasper is sometimes used as decorative aggregate. It has modest collector value unless unusually patterned or polished.

Geological facts

Red jasper is a variety of chert rather than a distinct mineral species. Its coloration commonly comes from finely dispersed hematite, while brown or yellow zones may contain goethite or limonite.

Field identification & locations

Identify it by its opaque red color, very fine texture, quartz-like hardness, and lack of acid reaction; it should scratch glass but not a steel file easily. Common sources include India, Madagascar, Brazil, the United States, and Australia.