sedimentary

Red Jasper (Chert)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Hardness: 6.5-7 on Mohs scale; Color: Opaque red/terracotta with white/brown banding; Luster: Dull to waxy; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91

Hardness: 6
Color: Opaque red/terracotta with white/brown banding
Luster: Dull to waxy

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils or precipitation from hydrothermal fluids in sedimentary environments. Its red color is derived from high iron content. It can be found in strata ranging from Precambrian to Cenozoic eras.

Uses & applications

Commonly used as a gemstone for jewelry (cabochons, beads), decorative carvings, lapidary practice, and historically for making tools/scrapers due to its sharp fracture edges.

Geological facts

Jasper has been a favorite gemstone since antiquity; it is mentioned in any ancient texts and used in the Minoan civilization of Crete for seals and jewelry. The name comes from the Greek 'iaspis', meaning 'spotted stone'.

Field identification & locations

Identify in the field by its opaque nature (unlike agate), smooth waxy feel when wet, and characteristic curved 'clamshell' (conchoidal) fractures. Often found in riverbeds or gravel pits in volcanic or sedimentary regions.

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