sedimentary
Jasper (likely Ocean Jasper or Variegated Jasper)
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5–7 on the Mohs scale. Color: Multicolored, typically green, brown, and yellow with orbicular or mottled patterns. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6–2.9.
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5–7 on the Mohs scale. Color: Multicolored, typically green, brown, and yellow with orbicular or mottled patterns. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6–2.9.
Formation & geological history
Formed from the deposition of silica in groundwater within volcanic rock cavities or sedimentary fissures. The colors and patterns result from mineral inclusions like iron and manganese. Most high-quality orbicular jasper is found in deposits that are millions of years old.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons), interior decoration items (bookends), and as a popular focus for crystal healing and mineral collecting.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'Jasper' is derived from the Greek word 'iaspis', meaning spotted stone. It was a favorite gemstone in the ancient world, referenced in many civilizations for its supposed protective qualities.
Field identification & locations
Identify in the field by its opacity (it does not transmit light even on thin edges), its hardness (it will scratch glass), and its distinctive smooth, waxy fracture surface. Common locations include Madagascar, India, Brazil, and the Western USA (Oregon/Idaho).
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