metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron inclusions)
Hardness: 6.5–7 (Mohs scale); Color: Golden yellow, honey brown, reddish-brown, and blue-gray; Luster: Silky; Crystal Structure: Trigonal (fibrous aggregate); Cleavage: None; Specific Gravity: 2.64–2.71
- Hardness
- 6
- Color
- Golden yellow, honey brown, reddish-brown, and blue-gray
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Golden yellow, honey brown, reddish-brown, and blue-gray; Luster: Silky; Crystal Structure: Trigonal (fibrous aggregate); Cleavage: None; Specific Gravity: 2.64–2.71
Formation & geological history
Formed through the pseudomorphism of crocidolite (blue asbestos) by silica. The original fibrous structure is preserved while the asbestos is replaced by quartz. Iron oxides provide the golden-brown coloration. Generally found in Precambrian banded iron formations.
Uses & applications
Primarily used in jewelry (beads, cabochons, carvings), decorative ornaments, and healing stone collections. It is occasionally used for small inlay work in furniture or boxes.
Geological facts
Exhibits a unique optical effect known as chatoyancy (cat's eye effect) caused by the parallel reflection of light off the internal fibrous structure. Variations include Hawk's Eye (blue) and Bull's Eye (heated red).
Field identification & locations
Identify by its distinct chatoyant 'shimmer' when rotated under light and its fibrous texture within a hard quartz matrix. Major sources include South Africa, Australia, Burma, India, and Namibia.
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