Jasper is a massive, fine-grained, opaque variety of chalcedony. It is believed to protect against sight of defects and drought. Jasper occurs in shades of greyish blue, brown, yellow, red, and green, and mixtures of these. Orbicular japser has white or grey, eye-shaped patterns surrounded by red jasper. Riband jasper, on the other hand, is striped and used in carvings, intaglios, and cameos.
These show off its layered structure. Besides, hornstone is the grey variety.
A jasper stone may break easily at junction of stripes. In nature, it may occur in a mammillated habit. It is common to find white quartz veins in the crystal. A jasper stone gets its red color due to the presence of iron oxide.
Occurrence
Red jasper occurs in India and Venezuela. Various colors are found in the USA, especially orbicular jasper in California. Red and green riband jasper occurs in Russia, Germany, and France.
Jasper Properties
- Specific Gravity: 2.61
- Refractive Index: 1.53-1.54
- Birefringence (DR): 0.004
- Luster: Vitreous
- Crystal Structure: Trigonal
- Composition: Silicon dioxide
- Hardness: 7
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