sedimentary

Banded Jasper (Chert)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown and grayish-green distinct bands; Luster: Waxy to vitreous when wet or polished; Structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.

Hardness: 6
Color: Reddish-brown and grayish-green distinct bands
Luster: Waxy to vitreous when wet or polished

Identified July 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms in sedimentary or low-grade metamorphic environments through the precipitation of silica-rich microcrystals within fine-grained sediments or volcanic ash, with variable iron oxide impurities creating distinct colored banding.

Uses & applications

Used in lapidary work, cabochon cutting, decorative carvings, tumbling, and as ornamental or collector specimens.

Geological facts

Jasper has been used for thousands of years in jewelry, amulets, and seals. The rich red bands are typically caused by hematite (iron oxide) inclusions, while green or gray bands usually result from iron silicates or chlorite.

Field identification & locations

Identify by its hardness (scratches glass, cannot be scratched by steel), smooth conchoidal fracture, opaque appearance, and distinct colorful banding. Common in river beds, gravel pits, and volcanic areas worldwide.