sedimentary
Jasper (Green Jasper/Heliotrope variety)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Dark green with possible red or yellow inclusions, Luster: Vitreous to waxy, Crystal Structure: Microcrystalline/Cryptocrystalline (Trigonal), Specific Gravity: 2.6-2.9
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Dark green with possible red or yellow inclusions, Luster: Vitreous to waxy, Crystal Structure: Microcrystalline/Cryptocrystalline (Trigonal), Specific Gravity: 2.6-2.9
Formation & geological history
Formed through the precipitation of silica from mineral-rich fluids in volcanic ash or sedimentary deposits, often occurring in hydrothermal veins or as nodules in volcanic rock.
Uses & applications
Used primarily in lapidary arts for cabochons, beads, and decorative carvings; historically used for signet rings and as a gemstone (Bloodstone variety).
Geological facts
Green jasper has been used since antiquity; the 'Bloodstone' variety with red spots was once believed by medieval Christians to represent the blood of Christ. It is a dense, opaque variety of chalcedony.
Field identification & locations
Identify in the field by its opaque nature (unlike translucent agate), conchoidal fracture (smooth, curved breaks), and its inability to be scratched by a steel knife. Commonly found in riverbeds and coastal areas in regions with volcanic history.
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