sedimentary

Red jasper / iron-rich chert

Microcrystalline quartz (SiO₂) colored by hematite/goethite

AI-generated identification · may be incorrect

Typically Mohs 6.5–7, opaque red-orange to gray, with a dull to waxy luster and very fine-grained, cryptocrystalline structure; no visible cleavage and irregular conchoidal fracture. The image suggests a thin, weathered or naturally broken fragment, though exact identification is uncertain from the photograph.

Identified August 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich sediment or volcanic material is silicified and stained by iron oxides, commonly during diagenesis or low-temperature hydrothermal alteration. It may range from Precambrian to much younger deposits, depending on locality.

Uses & applications

Used as decorative stone, lapidary material, beads, cabochons, carvings, and occasionally aggregate. Attractive patterned pieces have modest collector value.

Geological facts

The red color commonly comes from finely dispersed hematite, while gray areas reflect quartz-rich matrix or weathering. It can resemble brick, slag, or painted material, so a fresh fracture and hardness test are useful.

Field identification & locations

Common in iron-rich sedimentary formations, volcanic terrains, and silica-rich gravels worldwide. A steel file should scratch it only with difficulty; it should scratch glass and show no fizz with dilute hydrochloric acid.