sedimentary
Banded Jasper
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7 (Mohs); Color: Yellow, tan, and dark grey bands; Luster: Vitreous to waxy; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Yellow, tan, and dark grey bands
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Yellow, tan, and dark grey bands; Luster: Vitreous to waxy; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed via the deposition of silica-rich fluids in volcanic ash or sedimentary layers. The banding indicates rhythmic deposition or changes in chemical impurities like iron (yellow/brown) and manganese or carbon (grey) during formation.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), river rock landscaping, and as a decorative collector's specimen.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'jasper' comes from the Greek word 'iaspis', meaning 'spotted stone'. It is often found as water-worn pebbles in stream beds.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a steel knife), opaque nature, and smooth, waxy texture when wet or polished. Often found in riverbeds and coastal areas globally.
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