metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
Hardness: 6.5–7 on Mohs scale; Color: Golden yellow to deep brown; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64–2.71.
- Hardness
- 6
- Color
- Golden yellow to deep brown
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Golden yellow to deep brown; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64–2.71.
Formation & geological history
Formed through a metamorphic process where quartz replaces the fibrous mineral crocidolite (blue asbestos) while retaining its structure, a process known as pseudomorphism. Iron oxidation provides the golden color. Ages vary by location, typically Proterozoic.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative carving, and as a popular gemstone for crystal collecting and metaphysical purposes.
Geological facts
It exhibits chatoyancy, the 'cat-eye' effect, caused by the reflection of light off the parallel mineral fibers. If the iron is not oxidized, the stone remains blue and is known as Hawk's Eye.
Field identification & locations
Identify in the field by its distinctive golden-brown bands and moving 'flash' (chatoyancy) when rotated under light. Commonly found in South Africa, Australia, and Brazil. Check for a waxy to silky feel and high hardness.
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