sedimentary
Jasper Breccia
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7 (Mohs). Color: Tan, brown, ochre, and black veins. Luster: Dull/Waxy (but polished in photo). Crystal structure: Microcrystalline/Trigonal. Cleavage: None, conchoidal fracture.
- Hardness
- 6
- Color
- Tan, brown, ochre, and black veins
- Luster
- Dull/Waxy (but polished in photo)
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Physical properties
Hardness: 6.5-7 (Mohs). Color: Tan, brown, ochre, and black veins. Luster: Dull/Waxy (but polished in photo). Crystal structure: Microcrystalline/Trigonal. Cleavage: None, conchoidal fracture.
Formation & geological history
Formed when jasper or chert is fractured by tectonic movements and subsequently cemented together by secondary silica or iron oxides in hydrothermal environments.
Uses & applications
Primarily used for lapidary work, jewelry, decorative cabochons, and as a collector's specimen due to its unique patterns.
Geological facts
The word 'breccia' comes from Italian, meaning 'loose gravel' or 'broken stone'. No two pieces are identical because the fracturing and re-cementing process creates chaotic, unique patterns.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel knife) and the visible angular fragments of rock cemented together by a matrix. Commonly found in riverbeds or near volcanic-sedimentary contact zones.
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