sedimentary
Green Jasper
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7 on Mohs scale; Color: Deep green with bands of lighter green and yellow-brown; Luster: Vitreous to waxy when wet/polished; Crystal structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Deep green with bands of lighter green and yellow-brown
- Luster
- Vitreous to waxy when wet/polished
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Deep green with bands of lighter green and yellow-brown; Luster: Vitreous to waxy when wet/polished; Crystal structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91.
Formation & geological history
Formed through the deposition of silica from hydrothermal solutions or in sedimentary environments. Green jasper often gets its color from silicate minerals like chlorite or actinolite. It is typically found in volcanic ash and sedimentary deposits where mineral-rich water replaced organic material or filled cavities.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), ornamental carvings, and as a popular specimen for rock collectors.
Geological facts
Jasper has been used as a gemstone since antiquity; green jasper was particularly prized in the ancient world for its supposed ability to bring rain and for use in cylinder seals. The banding seen in this specimen suggests rhythmic deposition of minerals.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel knife), smooth conchoidal fracture, and opaque nature. Commonly found in riverbeds, coastal areas, and regions with significant volcanic history like the Pacific Northwest of the USA, India, and Madagascar.
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