sedimentary

Red jasper (likely iron-rich chert)

Microcrystalline quartz, SiO₂, colored mainly by hematite/goethite

AI-generated identification · may be incorrect

Typically hardness 6.5–7, opaque red to brown, with waxy to dull luster and a dense, cryptocrystalline structure; conchoidal fracture and no cleavage. The specimen appears freshly fractured or roughly knapped, with a darker red interior and ochre-brown weathered edge.

Identified August 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich sediments or chemically precipitated silica become cemented and colored by iron oxides; deposits range from Precambrian to younger ages. Common in iron-formations, chert beds, volcanic-associated silica deposits, and river gravels.

Uses & applications

Used for cabochons, beads, carvings, polished ornaments, and lapidary tools; historically shaped into blades and scrapers. Ordinary pieces have modest collecting value.

Geological facts

Red color is usually caused by dispersed hematite rather than red crystals. Jasper is a variety of opaque chalcedony/chert, and boundaries with iron-rich chert can be gradual.

Field identification & locations

Identify by its opaque brick-red color, very fine grain, glassy conchoidal fracture, and inability to scratch with a steel knife; it should scratch ordinary glass. Common localities include India, Brazil, Australia, South Africa, and the western United States.