metamorphic
Tiger’s eye
Quartz (SiO₂) with fibrous crocidolite pseudomorphs and iron oxides
AI-generated identification · may be incorrectMohs hardness 6.5–7; golden-brown to dark brown chatoyant bands, vitreous-to-silky luster, microcrystalline quartz, no obvious cleavage; specific gravity about 2.6–2.7. The polished rounded shape appears tumbled and may show a blue-gray edge typical of mixed tiger’s-eye material.
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Physical properties
Mohs hardness 6.5–7; golden-brown to dark brown chatoyant bands, vitreous-to-silky luster, microcrystalline quartz, no obvious cleavage; specific gravity about 2.6–2.7. The polished rounded shape appears tumbled and may show a blue-gray edge typical of mixed tiger’s-eye material.
Formation & geological history
Forms when quartz replaces fibrous riebeckite/crocidolite during low-grade metamorphic alteration, with oxidation producing gold-brown colors. Major deposits occur in Precambrian rocks of South Africa, Western Australia, India, and Namibia.
Uses & applications
Used for cabochons, beads, carvings, ornaments, and inexpensive collector stones; rarely used in architectural decorative work.
Geological facts
Its moving band of reflected light is called chatoyancy, caused by aligned fibers and parallel inclusions. Blue, golden, and red varieties are commonly marketed as hawk’s-eye, tiger’s-eye, and red tiger’s-eye.
Field identification & locations
Identify by its silky parallel bands and strong cat’s-eye flash when rotated under a point light; glass imitations usually lack natural band variation. Commonly sold as polished or tumbled pieces.
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