Rock Identifier
Polished tiger’s eye (Quartz (microcrystalline SiO₂) with crocidolite-derived iron oxides) — mineral
mineral

Polished tiger’s eye

Quartz (microcrystalline SiO₂) with crocidolite-derived iron oxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; golden-brown to reddish-brown silky chatoyancy, vitreous to silky luster, and no prominent cleavage. Its fibrous quartz structure produces the moving cat’s-eye band when polished.

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Physical properties

Hardness 6.5–7 Mohs; golden-brown to reddish-brown silky chatoyancy, vitreous to silky luster, and no prominent cleavage. Its fibrous quartz structure produces the moving cat’s-eye band when polished.

Formation & geological history

A quartz replacement of crocidolite asbestos fibers, formed by silica-rich fluids during low-grade metamorphic alteration; commonly Precambrian, especially in South African deposits.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; valued mainly as a decorative gemstone.

Geological facts

The chatoyant effect is strongest when the stone is cut parallel to its fibrous structure. Blue hawk’s-eye is a less-oxidized precursor, while red tiger’s-eye reflects additional iron staining.

Field identification & locations

Identify it by its parallel golden bands and sharp, mobile reflective streak under directional light; it is commonly found in South Africa, Western Australia, India, and Brazil. Avoid confusing it with glass or synthetic cat’s-eye materials.