Tiger's Eye (Quartz): South Africa (rough mass ~ 3 inches long; blue and red cabochons are dyed). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Tiger's Eye Information
| Data | Value |
|---|---|
| Name | Tiger's Eye |
| Is a Variety of | Quartz |
| Varieties | Falcon's Eye |
| Crystallography | Hexagonal (trigonal) |
| Refractive Index | 1.544-1.553 |
| Colors | Golden brown (Tiger's eye); Blue (Hawk's eye); some pieces show both colors. |
| Luster | Vitreous. |
| Hardness | 7 |
| Wearability | Very Good |
| Fracture | Conchoidal |
| Specific Gravity | 2.55-2.91 |
| Birefringence | 0.009 |
| Cleavage | None |
| Dispersion | 0.013 |
| Enhancements | Bleaching, dyeing. Heat may create the eye effect. |
| Typical Treatments | Bleaching, Dyeing, Heat Treatment |
| Transparency | Opaque. |
| Absorption Spectrum | Not diagnostic. |
| Phenomena | Chatoyancy. |
| Optics | o = 1.544; e = 1.553 (very constant). Uniaxial (+). |
| Optic Sign | Uniaxial + |
Crocidolite, (blue asbestos,) alters to quartz, but while retaining its fibrous structure. This material is frequently stained by iron, giving it a golden brown color. We know this material as tigers eye. Unstained pieces, retaining their original blue color, are called Hawk’s Eye. There are also pieces with both colors.
Sources
Australia; China; Namibia; South Africa; England, UK; United States.
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