The eye of the tiger

Tyger! Tyger! burning bright
In the forests of the night,
What immortal hand or eye
Dare frame thy fearful symmetry?

William Blake 1794

This isn't, of course, they eye of a real tyger or, as we now call it, tiger. Rather it is a stone egg carved from the mineral tiger's eye.

Tiger's Eye is a form of quartz with some special characteristics. Like all quartz it is made up primarily of silicone dioxide, SiO2. Within this matrix are asbestos fibers usually occurring in layers. It is the asbestos that makes Tiger eye a chatoyant gemstone, meaning the fibers (asbestos) of the stone reflect in a wavering silky lustre that can resemble the eye of a cat.

The word Chatoyant comes from the French meaning “cat’s eye”.