polished stones · Medium — approx. 6–8 cm diameter
Tiger's Eye Sphere
A polished tiger's eye sphere — cut from solid tiger's eye and ground to a perfect sphere, then polished to high gloss. The defining characteristic of tiger's eye is chatoyancy: a cat's-eye optical effect produced by light reflecting off the parallel fibres of crocidolite that were replaced by quartz during the stone's formation. As you rotate a sphere, the silky band of light moves across the surface.
Tiger's eye is a pseudomorph — it formed when quartz replaced the fibres of a blue asbestos mineral (crocidolite) while retaining the fibrous structure. The golden-brown colour comes from iron oxide. Unoxidised material shows the original blue-grey (hawk's eye). Some pieces show both colours in bands.
A sphere shows chatoyancy from every angle as it rotates, which is why spheres are the preferred cut for tiger's eye. It is impossible to find a dead angle. Place it on a ring stand under a directional light source and the band will be visible from across the room.
Mineralogy & Properties
Quartz (SiO₂) pseudomorph after crocidolite, Iron oxide (golden-brown colour), Crocidolite fibre matrix (chatoyancy), Mohs hardness: 7, Origin: South Africa
Approximate diameter: 6–8 cm. Weight: 200–450 g. Origin: South Africa.
Mineral: Quartz pseudomorph after crocidolite. Colour: golden-brown with silky parallel fibres. Optical effect: chatoyancy (cat's-eye). Mohs hardness: 7. Crystal system: trigonal (quartz). High-gloss sphere with ring stand included.
- Dimensions
- Medium — approx. 6–8 cm diameter
- Weight
- 200–450 g