sedimentary
Jasper
Silicon dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale). Color: Earthy red, brown, yellow. Luster: Dull to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None, conchoidal fracture. Specific gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Earthy red, brown, yellow
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs scale). Color: Earthy red, brown, yellow. Luster: Dull to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None, conchoidal fracture. Specific gravity: 2.58-2.91.
Formation & geological history
Formed through the accumulation of fine siliceous material from volcanic ash or micro-plankton (radiolitids) in sedimentary environments. Its appearance is often a result of iron impurities mineralizing over millions of years.
Uses & applications
Commonly used as a gemstone for jewelry (cabochons), interior decoration, ornamental carvings, and historical use as striking stones for flintlock weapons.
Geological facts
Jasper has been used by humans since antiquity; the name is derived from the Greek word 'iaspis', meaning spotted stone. It was a favorite gemstone in the ancient world, mentioned in both Greek and Biblical literature.
Field identification & locations
Identify by its opacity (even on thin edges), smooth conchoidal fracture, and inability to be scratched by a steel knife. Frequently found in riverbeds and desert environments.
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