Tiger's Eye vs. Hawk's Eye: What's the Difference?

Tiger's eye and hawk's eye are both quartz pseudomorphs after crocidolite, a fibrous form of the mineral riebeckite (part of the amphibole group). "Pseudomorph" means silica gradually replaced the original crocidolite fibers while preserving their fibrous structure — and that preserved fibrous structure is exactly what produces chatoyancy, the silky, moving band of light that shifts across the stone as it's turned, sometimes called the "cat's eye" effect.

Oxidized vs. Unoxidized

The difference between tiger's eye and hawk's eye comes down to oxidation. Tiger's eye has been oxidized, converting its iron content to iron oxide and turning the stone golden-brown to reddish-brown. Hawk's eye hasn't undergone that oxidation, so it retains a blue-grey to blue-green color instead — both are the same underlying mineral structure, just at different stages of the same chemical process.

Why the Chatoyancy Effect Happens

The parallel fibrous structure inherited from the original crocidolite acts almost like a bundle of tiny optical fibers: light entering the stone reflects off these aligned fibers, and because they all run in the same direction, the reflection concentrates into a single band that appears to move as the angle of light or viewing shifts. Cutting the stone as a rounded cabochon, with the dome aligned across the fiber direction, maximizes this effect — a flat-cut stone shows much less chatoyancy than a properly oriented cabochon.

"Tiger Iron"

A related material called tiger iron combines tiger's eye with bands of hematite and jasper, giving a striped, layered appearance rather than tiger's eye's more uniform chatoyant surface — it's a genuinely different composite material, not simply a variety of tiger's eye.

Where It's Mined

South Africa's Northern Cape province is the dominant global source for both tiger's eye and hawk's eye, with additional deposits in Western Australia, India, Myanmar and Brazil.

Quick Facts

Mineral family: quartz pseudomorph after crocidolite — Hardness: 7 on the Mohs scale — Color cause: iron oxidation state — Major source: South Africa.