sedimentary
Jasper
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7 (Mohs). Color: Red, brown, and yellow mottling. Luster: Dull to vitreous. Crystal Structure: Microcrystalline quartz (Trigonal). Cleavage: None (Conchoidal fracture). Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Red, brown, and yellow mottling
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs). Color: Red, brown, and yellow mottling. Luster: Dull to vitreous. Crystal Structure: Microcrystalline quartz (Trigonal). Cleavage: None (Conchoidal fracture). Specific Gravity: 2.58-2.91.
Formation & geological history
Formed when silica-rich fluids permeate through volcanic ash or sedimentary deposits, crystallizing over long periods. Often associated with Precambrian to Mesozoic geological ages.
Uses & applications
Commonly used as a gemstone in jewelry, for lapidary work (cabochons), and as an ornamental stone in home decor and carvings.
Geological facts
The name comes from the Greek word 'iaspis', meaning spotted stone. It is an opaque variety of chalcedony. Historically, jasper was believed to provide physical and spiritual protection by ancient civilizations.
Field identification & locations
Identify in the field by its opacity (even when held to light), smooth conchoidal fracture, and inability to be scratched by a steel knife. Commonly found in riverbeds and desert environments.
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