metamorphic

Tumbled tiger’s-eye

Quartz (SiO₂), fibrous golden-brown variety with crocidolite pseudomorphs

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; golden-brown to black, vitreous and silky chatoyant luster, opaque to translucent. The polished, rounded shape indicates tumbling; visible dark areas may be matrix or iron-rich alteration.

Identified September 2, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when fibrous crocidolite asbestos is replaced by quartz during hydrothermal alteration, commonly in Precambrian metamorphic rocks; major deposits occur in South Africa, Australia, India, and Namibia.

Uses & applications

Used for cabochons, beads, carvings, worry stones, and ornamental objects; not generally used as an industrial aggregate in this polished form.

Geological facts

Its moving band of reflected light is called chatoyancy and results from aligned fibers. Brown-gold color comes largely from iron oxidation, while blue-gray material is called hawk’s-eye.

Field identification & locations

Identify by its silky, directional banding and strong cat’s-eye effect when rotated under a focused light; glass and jasper usually lack this fiber-like reflection. Common specimens are widely sold as tumbled stones.