sedimentary
Jasper (Banded Jasper / Chert)
Silicon Dioxide (SiO2 with iron oxide inclusions)
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
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Physical properties
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.
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.
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