sedimentary
Jasper
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Dark green/grey with subtle inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Dark green/grey with subtle inclusions
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Dark green/grey with subtle inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
Formation & geological history
Formed primarily from the deposition of silica from water solutions into cracks and voids in volcanic or sedimentary rocks. This specimen appears to be a water-worn or tumbled pebble.
Uses & applications
Used extensively for lapidary work, jewelry (beads, cabochons), ornamental stone, and as a pocket stone for collectors.
Geological facts
Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning spotted stone. It has been used for seals and amulets since ancient times.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel knife), opaque nature, and smooth, waxy surface when polished. Found globally in riverbeds or coastal areas.
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