Rock Identifier
Tiger's Eye (Rough) (SiO2 (Silicon Dioxide / Pseudomorph of Quartz after Crocidolite)) — Mineral / Metamorphic
Mineral / Metamorphic

Tiger's Eye (Rough)

SiO2 (Silicon Dioxide / Pseudomorph of Quartz after Crocidolite)

Hardness: 7 on Mohs scale; Color: Golden to brown with chatoyant yellow bands; Luster: Silky; Crystal System: Trigonal; Cleavage: None; Specific Gravity: 2.64-2.71.

Hardness
7 on Mohs scale
Color
Golden to brown with chatoyant yellow bands
Luster
Silky
Identified More mineral / metamorphic

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Physical properties

Hardness: 7 on Mohs scale; Color: Golden to brown with chatoyant yellow bands; Luster: Silky; Crystal System: Trigonal; Cleavage: None; Specific Gravity: 2.64-2.71.

Formation & geological history

Formed when quartz replaces the blue crocidolite (asbestos) fibers through a process called pseudomorphism, while retaining the fibrous structure. Primarily found in Precambrian iron formations (approx. 2 billion years old).

Uses & applications

Predominantly used for lapidary work, jewelry (cabochons and beads), ornamental carvings, and as a popular specimen for crystal collectors and 'metaphysical' retail.

Geological facts

The characteristic 'cat's eye' effect is called chatoyancy. When the fibers remain blue rather than turning brown/gold through oxidation, the mineral is known as 'Hawk's Eye'.

Field identification & locations

Identify in the field by its distinctive silky luster and alternating dark/light bands that shift as the stone is rotated under light. Most commonly found in the Griqualand West region of South Africa and the Pilbara region of Australia.