sedimentary

Jasper (Banded Jasper / Chert)

Silicon Dioxide (SiO2 with iron oxide inclusions)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on the Mohs scale; Color: Brownish-yellow, tan, reddish-brown with visible banding; Luster: Waxy to vitreous when wet or polished; Fracture: Conchoidal; Cleavage: None; Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Brownish-yellow, tan, reddish-brown with visible banding
Luster: Waxy to vitreous when wet or polished

Identified July 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of microcrystalline quartz or silica-rich fluids in sedimentary layers or volcanic cavities, often altered by iron oxide mineral precipitates over millions of years.

Uses & applications

Popular for lapidary work, cabochon cutting, stone tumbling, decorative carvings, and rock collecting.

Geological facts

Banded jasper often forms distinct stripe-like layers due to episodic deposition of silica and variable levels of iron mineralization during its formation process.

Field identification & locations

Can be identified in the field by its smooth, river-worn exterior, waxy luster when wet, distinct color banding, and smooth conchoidal fracturing. Widely found along gravel bars, river beds, and coastal beaches.