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 (Quartz): South Africa (rough mass ~ 3 inches long; blue and red cabochons are dyed). Photo © Joel E. Arem, PhD, FGA. Used with permission.
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.