sedimentary
Jasper
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7 Mohs; Color: Dull green and brownish-red; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Dull green and brownish-red
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Dull green and brownish-red; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Forms through the deposition of silica from water into cracks or cavities in other rocks, often during low-temperature hydrothermal processes or from volcanic ash.
Uses & applications
Used primarily for lapidary work, jewelry, ornamental carvings, and as a decorative stone in aquariums and landscaping.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'jasper' comes from the Old French word 'jaspre', meaning 'spotted or speckled stone'.
Field identification & locations
Field identification involves its extreme hardness (scratches glass), opaque appearance, and classic smooth, shell-like (conchoidal) fracture surfaces seen in this specimen.
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