sedimentary
Jasper (Nephrite-like appearance)
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7 on Mohs scale. Color: Deep dark green to black-green. Luster: Vitreous to waxy when polished. Crystal structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.6-2.9.
- Hardness
- 6
- Color
- Deep dark green to black-green
- Luster
- Vitreous to waxy when polished
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Deep dark green to black-green. Luster: Vitreous to waxy when polished. Crystal structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.6-2.9.
Formation & geological history
Formed from the deposition of silica from water solutions into cavities of other rocks or as replacement material. Often smoothed by fluvial or marine erosion.
Uses & applications
Used primarily for lapidary work, jewelry, pocket stones, and decorative carvings. It is also a popular stone for tumbling.
Geological facts
Dark green jasper was historically known as 'heliotrope' or 'bloodstone' if it had red spots. This specific uniform dark green variety is often sold as 'Evergreen Jasper'.
Field identification & locations
Identify in the field by its opacity (jasper is opaque), smooth water-worn texture, and hardness (cannot be scratched by a steel knife). Commonly found in riverbeds and along beaches.
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