Rock Identifier
Lepidolite and Tiger's Eye (K(Li,Al)3(Si,Al)4O10(F,OH)2 (Lepidolite) / SiO2 (Quartz/Tiger's Eye)) — mineral
mineral

Lepidolite and Tiger's Eye

K(Li,Al)3(Si,Al)4O10(F,OH)2 (Lepidolite) / SiO2 (Quartz/Tiger's Eye)

Lepidolite: Hardness 2.5-3.0, lilac to rose-pink or purple color, pearly to vitreous luster, monoclinic crystal system, perfect basal cleavage. Tiger's Eye: Hardness 7, golden-yellow to red-brown color, silky luster, trigonal crystal system, chatoyant visual effect.

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Physical properties

Lepidolite: Hardness 2.5-3.0, lilac to rose-pink or purple color, pearly to vitreous luster, monoclinic crystal system, perfect basal cleavage. Tiger's Eye: Hardness 7, golden-yellow to red-brown color, silky luster, trigonal crystal system, chatoyant visual effect.

Formation & geological history

Lepidolite forms in lithium-bearing granitic pegmatites. Tiger's Eye forms when quartz replaces crocidolite (blue asbestos) fibers through pseudomorphism, maintaining the fibrous structure.

Uses & applications

Lepidolite is a major ore of lithium used in batteries, glass, and ceramics. Tiger's Eye is popular for lapidary work, cabochons, beads, carvings, and jewelry. Both are widely collected.

Geological facts

Lepidolite is one of the primary sources of lithium, the lightest metal on Earth. Tiger's Eye displays a beautiful optical phenomenon called chatoyancy, or the cat's-eye effect.

Field identification & locations

Lepidolite can be identified by its scaly mica-like structure, soft hardness, and distinctive pinkish-purple color. Tiger's Eye is identified by its golden-brown color band and silky luster chatoyancy. Found in South Africa, Australia, Brazil, Canada, and Madagascar.