metamorphic
Tiger's Eye
SiO2 (Pseudomorph of Quartz after Crocidolite)
Hardness: 6.5-7 (Mohs scale); Color: Golden-yellow to brown; Luster: Silky to vitreous; Crystal structure: Trigonal; Chatoyancy (cat's eye effect); Specific Gravity: 2.64-2.71
- Hardness
- 6
- Color
- Golden-yellow to brown
- Luster
- Silky to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Golden-yellow to brown; Luster: Silky to vitreous; Crystal structure: Trigonal; Chatoyancy (cat's eye effect); Specific Gravity: 2.64-2.71
Formation & geological history
Formed through the replacement of fibrous crocidolite (blue asbestos) with silica (quartz), a process known as pseudomorphism. Most deposits are billions of years old, typically found in iron formations.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative carvings, collected as semi-precious gemstones, and used in metaphysical practices.
Geological facts
The chatoyant effect is caused by the parallel arrangement of the original asbestos fibers that were replaced by quartz. This specific variety with golden-brown hues is created when iron oxides are present; if the iron is absent, it remains blue (Hawk's Eye).
Field identification & locations
Identify by its distinct golden-brown bands that seem to shift and shimmer when moved under a light source (chatoyancy). It is commonly found in South Africa and Western Australia.
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