Rock Identifier
Tiger's Eye (Rough) (Silicon Dioxide (SiO2) with fibrous crocidolite / Limonite inclusions) — Mineral (Metamorphic pseudomorph)
Mineral (Metamorphic pseudomorph)

Tiger's Eye (Rough)

Silicon Dioxide (SiO2) with fibrous crocidolite / Limonite inclusions

Hardness: 6.5-7 (Mohs scale), Color: Golden brown to brownish-yellow, Luster: Silky/Vitreous, Crystal structure: Trigonal (fibrous texture), Cleavage: None, Specific Gravity: 2.64-2.71

Hardness
6

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Golden brown to brownish-yellow, Luster: Silky/Vitreous, Crystal structure: Trigonal (fibrous texture), Cleavage: None, Specific Gravity: 2.64-2.71

Formation & geological history

Formed through the pseudomorphism of crocidolite (asbestos) fibers by silica (quartz). Iron within the structures oxidizes to limonite, giving it the golden hue. Most deposits are Proterozoic in age (approx. 2 billion years old).

Uses & applications

Primarily used for lapidary work, jewelry (cabochons and beads), ornamental carvings, and as a popular semi-precious stone for collectors due to its chatoyancy.

Geological facts

It is a ‘pseudomorph,’ meaning it formed when one mineral replaced another while retaining the original shape. When cut and polished, it exhibits chatoyancy, the 'cat-eye' effect where a band of light moves across the stone.

Field identification & locations

Identify in the field by its distinct fibrous, parallel bands of gold and dark brown and its silky sheen even in rough form. Found predominantly in South Africa (Griqualand West), Western Australia, and parts of India and Brazil.