sedimentary
Chert / Jasper
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Variegated brown, yellow, and green, Luster: Waxy to dull, Crystal Structure: Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Variegated brown, yellow, and green, Luster: Waxy to dull, Crystal Structure: Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the accumulation of silica-rich microfossils or precipitation from silica-rich fluids in sedimentary environments. Can be found in various geological ages ranging from Precambrian to Cenozoic.
Uses & applications
Used as lapidary material for jewelry, decorative stones, and historically for making sharp tools like arrowheads and scrapers due to its conchoidal fracture.
Geological facts
Jasper is an opaque variety of chalcedony that gets its color from mineral impurities, primarily iron oxides. It has been used as a gemstone since antiquity.
Field identification & locations
Identify by its hardness (scratches glass), waxy luster when wet or polished, and smooth, curved fracture surfaces. Commonly found in riverbeds, glacial deposits, and sedimentary formations globally.
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