sedimentary

Jasper (Red Jasper)

Jasper (SiO2 - Silicon Dioxide with iron inclusions)

Hardness: 6.5-7 (Mohs scale); Color: Deep reddish-brown to terracotta; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.

Hardness: 6
Color: Deep reddish-brown to terracotta
Luster: Dull to waxy

Identified March 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from silica-rich groundwater that circulates through sedimentary or volcanic rocks, precipitating in voids. Its distinctive color comes from significant iron oxide (hematite) inclusions incorporated during the mineralization process.

Uses & applications

Used primarily for ornamental jewelry (cabochons, beads), decorative objects, lapidary art, and historically used for stone tools due to its conchoidal fracture pattern.

Geological facts

Jasper was a favorite gem in antiquity; it is mentioned in the Bible and was used in the breastplate of the High Priest. The name is derived from the Greek 'iaspis', meaning spotted stone.

Field identification & locations

Identify in the field by its opacity, red streak (if high in iron), and glass-like curved fractures when broken. It cannot be scratched by a steel knife. Common in diverse locations including the USA (Western states), India, Brazil, and Egypt.

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