metamorphic

Tumbled tiger’s eye

Quartz (SiO₂) with fibrous riebeckite/crocidolite inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; golden-brown chatoyant bands, vitreous to silky luster, microcrystalline quartz, no obvious cleavage, specific gravity about 2.64–2.71. The polished surface shows a reflective cat’s-eye effect from aligned fibers.

Identified August 16, 2026More metamorphic →

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Physical properties

Formation & geological history

A metamorphic quartz aggregate formed when crocidolite fibers were replaced and encased by silica during alteration, commonly in iron-rich environments. Most commercial material comes from the Precambrian formations of South Africa and Western Australia.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; it is popular in inexpensive jewelry and collections.

Geological facts

Its chatoyancy changes with viewing angle because light reflects from parallel fibrous inclusions. Blue-gray unaltered material is called hawk’s eye, while red-brown heat-treated material is often called ox-eye.

Field identification & locations

Identify it by its silky golden bands and moving cat’s-eye sheen, unlike uniformly colored glass or ordinary quartz. Common sources include South Africa, Western Australia, India, Brazil, and the United States.