mineral
Tiger's Eye (dark/grey variant)
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5-7.0 (Mohs); Color: Dark grey, brownish-black with chatoyancy; Luster: Silky; Crystal Structure: Trigonal/Fibrous; Specific Gravity: 2.64-2.71
- Hardness
- 6
- Color
- Dark grey, brownish-black with chatoyancy
- Luster
- Silky
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Physical properties
Hardness: 6.5-7.0 (Mohs); Color: Dark grey, brownish-black with chatoyancy; Luster: Silky; Crystal Structure: Trigonal/Fibrous; Specific Gravity: 2.64-2.71
Formation & geological history
Formed through a metamorphic process where quartz replaces the asbestos mineral crocidolite via pseudomorphism. This maintains the fibrous structure responsible for the optical effect.
Uses & applications
Primarily used for jewelry (cabochons, beads), decorative carvings, and as a popular meditation or collector's stone.
Geological facts
The shimmering effect seen in this stone is called chatoyancy. While the gold/brown variety is most common, darker variants like this can occur naturally or through heat treatment.
Field identification & locations
Identify by rotating under light to observe the moving silky band (chatoyancy). It is commonly found in South Africa and Western Australia. Collectors look for sharp, clean bands.
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