sedimentary
Jasper (Mookaite variety likely)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale); Color: Earthy reds, browns, tan, and cream; Luster: Dull to vitreous/waxy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Earthy reds, browns, tan, and cream
- Luster
- Dull to vitreous/waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Earthy reds, browns, tan, and cream; Luster: Dull to vitreous/waxy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
Formation & geological history
Jasper forms when silica-rich fluids permeate porous sediment or volcanic ash, slowly replacing organic or mineral matter with microcrystalline quartz. This specimen shows water-worn smoothing and iron-rich banding consistent with alluvial or stream-bed deposition.
Uses & applications
Used primarily in lapidary arts for cabochons, beads, and ornamental carvings. Due to its hardness, it is also popular as a tumbling stone for beginning collectors and in metaphysical jewelry.
Geological facts
Jasper has been used for millennia; the ancient Egyptians used it for talismans and amulets. It is an opaque variety of chalcedony, and its name is derived from the Greek 'iaspis', meaning spotted stone.
Field identification & locations
Identify in the field by its opacity (does not transmit light), conchoidal (shell-like) fracture patterns if chipped, and inability to be scratched by a steel knife. Frequently found in gravel beds, stream banks, and desert pavement across the globe, notably in Western Australia (Mookaite variety) and the Western US.
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