mineral

Chatoyant Quartz (Cat's Eye Quartz)

Silicon Dioxide (SiO2) with fibrous inclusions of Amphibole or Rutile

Hardness: 7 on Mohs scale; Color: Grayish-white, tan, or smoky; Luster: Vitreous to silky; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Grayish-white, tan, or smoky
Luster: Vitreous to silky

Identified February 14, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grayish-white, tan, or smoky; Luster: Vitreous to silky; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed through the hydrothermal deposition of silica within rock cavities. The chatoyant effect (cat's eye) occurs when light reflects off parallel fibrous inclusions of minerals like crocidolite or asbestiform minerals that have been replaced by quartz.

Uses & applications

Primarily used in jewelry as cabochons to highlight the optical effect, in crystal healing practices, and as a collector's specimen.

Geological facts

This optical phenomenon is called chatoyancy, derived from the French 'oeil de chat'. While chrysoberyl is the most famous cat's eye, quartz is the most common mineral to exhibit this effect naturally.

Field identification & locations

Identify in the field by rotating the stone under a single light source to see a band of light move across the surface. Frequently found in Brazil, India, Sri Lanka, and Madagascar.

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