metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of Iron Oxide)
Hardness: 6.5–7 (Mohs); Color: Golden-brown, amber, honey-yellow; Luster: Silky/Vitreous; Crystal Structure: Trigonal (Hexagonal); Cleavage: None; Specific Gravity: 2.64–2.71; Notable for chatoyancy (cat-eye effect).
- Hardness
- 6
- Color
- Golden-brown, amber, honey-yellow
- Luster
- Silky/Vitreous
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Physical properties
Hardness: 6.5–7 (Mohs); Color: Golden-brown, amber, honey-yellow; Luster: Silky/Vitreous; Crystal Structure: Trigonal (Hexagonal); Cleavage: None; Specific Gravity: 2.64–2.71; Notable for chatoyancy (cat-eye effect).
Formation & geological history
Formed through a metamorphic process where quartz replaces the fibrous mineral crocidolite (blue asbestos) over time while preserving the original fibrous structure. Iron within the mineral oxidizes to produce the characteristic gold-brown colors.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative carvings, lapidary arts, and as a popular specimen for crystal collecting due to its aesthetic chatoyancy.
Geological facts
Historically, Roman soldiers carried Tiger's Eye for protection in battle. It is a 'pseudomorph,' meaning it has the chemical composition of one mineral (Quartz) but retains the physical shape and structure of another (Crocidolite).
Field identification & locations
Identify in the field by its distinct parallel banding and 'shimmer' when rotated under light. Common locations include South Africa (Cape Province), Western Australia, India, and Namibia. Collectors should look for high-contrast banding and a strong silky luster.
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