Rock Identifier
Tiger’s-eye (Chatoyant quartz (SiO₂), commonly pseudomorphic quartz after crocidolite) — mineral
mineral

Tiger’s-eye

Chatoyant quartz (SiO₂), commonly pseudomorphic quartz after crocidolite

AI-generated identification · may be incorrect

Typically golden-brown with silky chatoyancy from aligned fibrous inclusions; Mohs hardness 6.5–7, vitreous to silky luster, no prominent cleavage, and specific gravity about 2.64–2.71. The specimen appears polished or freshly cut.

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Physical properties

Typically golden-brown with silky chatoyancy from aligned fibrous inclusions; Mohs hardness 6.5–7, vitreous to silky luster, no prominent cleavage, and specific gravity about 2.64–2.71. The specimen appears polished or freshly cut.

Formation & geological history

Forms when quartz replaces crocidolite asbestos fibers during hydrothermal alteration, preserving their alignment; generally associated with Proterozoic metamorphic rocks, especially in South Africa and western Australia.

Uses & applications

Widely used for cabochons, beads, carvings, ornamental objects, and lapidary specimens; its distinctive moving band of light makes it popular in jewelry.

Geological facts

Chatoyancy means “cat’s-eye” optical effect and is strongest when the stone is cut parallel to the fibers. Blue-gray hawk’s-eye and red-brown oxidized varieties are related forms.

Field identification & locations

Identify it by the sharp, mobile golden band that shifts with light, fibrous silky texture, and hardness sufficient to scratch glass; distinguish it from synthetic glass by its natural banding and inclusions. Common sources include South Africa, Australia, India, and Brazil.