mineral
Polished tiger’s-eye
Quartz variety, SiO₂, with crocidolite-derived iron inclusions
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; golden-brown to dark brown chatoyant bands, vitreous-to-silky luster, massive microcrystalline quartz, no visible cleavage, specific gravity about 2.6–2.7. The polished surface produces a reflective cat’s-eye effect when moved under light.
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Physical properties
Hardness 6.5–7 Mohs; golden-brown to dark brown chatoyant bands, vitreous-to-silky luster, massive microcrystalline quartz, no visible cleavage, specific gravity about 2.6–2.7. The polished surface produces a reflective cat’s-eye effect when moved under light.
Formation & geological history
Forms when blue asbestos-like crocidolite fibers in quartz are replaced by quartz and oxidized to limonite/goethite, preserving fibrous structure; most gem-quality material formed in Precambrian rocks. Major deposits are in South Africa, Western Australia, India, Namibia, and the United States.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, ornaments, and inexpensive jewelry; rarely used industrially because it is valued mainly as a decorative gemstone.
Geological facts
Tiger’s-eye is a pseudomorph: quartz replaces fibrous material while retaining its texture. Blue-gray hawk’s-eye and reddish heat-treated material are related varieties.
Field identification & locations
Identify it by parallel silky bands and strong chatoyancy, unlike ordinary brown quartz; it should not show the granular texture of wood or plastic. Inspect under a focused light and check its glassy hardness, while avoiding confusing dyed glass or synthetic imitations.
