sedimentary
Jasper (likely Iron-stained)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, ochre, and rust; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); SG: 2.58-2.91
- Hardness
- 6
- Color
- Brown, tan, ochre, and rust
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, ochre, and rust; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); SG: 2.58-2.91
Formation & geological history
Formed from the deposition of silica-rich fluids in volcanic ash or sedimentary beds, often during the Proterozoic to Cenozoic eras. The color comes from iron impurities oxidized in deep hydrothermal or sedimentary environments.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), interior decoration, and as a popular specimen for rock tumbling and collecting.
Geological facts
Jasper is an opaque variety of chalcedony. It has been used since antiquity for seals, amulets, and ornaments, and is mentioned in many ancient texts as a stone of protection.
Field identification & locations
Identify in the field by its opaque nature, smooth waxy texture when broken, and inability to be scratched by a steel knife. Frequently found in riverbeds and desert environments globally.
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