Gemstone profile and identification guide

Cat's Eye Moonstone

Cat's-eye moonstone is moonstone-type feldspar showing a chatoyant band in suitable cabochon orientation.

6 Mohs White, Blue Sheen Feldspar (Moonstone Variety with Chatoyancy)

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Overview

Cat's-eye moonstone is moonstone-type feldspar showing a chatoyant band in suitable cabochon orientation.

Did you know? Chatoyant moonstone is less common than standard adularescent moonstone.

Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.

Identification

Name: Cat's Eye Moonstone

Scientific classification: Feldspar (Moonstone Variety with Chatoyancy)

Hardness: 6 Mohs

Transparency: translucent

Lustre: pearly

Crystal system: Monoclinic/triclinic feldspar intergrowth context

Primary colour: White

Secondary colour: Blue Sheen

Colour family: Whites & Neutrals

Combination of feldspar properties with eye effect and possible adularescence is diagnostic.

Verification Status

Status: verified-core-fields

Reference priority: GIA, Gem-A, Mindat, International Gem Society

Core identity, locality, and physical-property fields reviewed against standard gemological references.

Values are reported as practical gemological ranges where appropriate.

Physical Properties

Hardness category: hard

Hardness value: 6 Mohs

Chemical composition: (K,Na)AlSi3O8 feldspar intergrowth

Crystal system: Monoclinic/triclinic feldspar intergrowth context

Common locations: Sri Lanka, India, Madagascar, Myanmar

Learn more: Gem-A gemstone education resources.

Colour Variations

Moonstone-type feldspar showing a cat's-eye effect, often with pale body colour.

Optical effects: Chatoyancy, Adularescence

Detailed Gemology

Mineral species: Moonstone-type feldspar intergrowth

Mineral group: Feldspar group

Chemical formula: (K,Na)AlSi3O8 feldspar intergrowth

Mohs hardness: 6

Crystal system: Monoclinic/triclinic feldspar intergrowth context

Lustre: pearly

Transparency: translucent

Streak: White

Cleavage: Perfect in two directions

Fracture: Uneven

Specific gravity: 2.55-2.62

Refractive index: 1.518-1.526 (orthoclase-rich moonstone context)

Optical phenomena: Chatoyancy and adularescence

Colour range: White, grey, colorless with sheen

Common inclusions: Lamellae, aligned inclusions, cleavage traces

Geological environment: Pegmatitic and feldspar-rich igneous environments

Principal mining regions: Sri Lanka, India, Madagascar, Myanmar

Important commercial sources: Chatoyant moonstone material is sourced from key moonstone-producing regions in South Asia and Madagascar

Historical significance: Niche collector and jewellery material within moonstone trade.

Common treatments: Some lower-grade material may be coated or filled.

Synthetic or imitation forms: Glass and synthetic sheen materials may imitate effect.

Common look-alikes: Cat's-eye quartz, opalite glass, labradorite effects

Jewellery uses: Used in cabochons for jewellery and collector optical-effect stones.

Care recommendations: Moderate hardness with cleavage; use protective settings and avoid impact.

Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Cat's Eye Moonstone.

Formation

Forms from feldspar intergrowth structures and aligned inclusions that produce sheen and eye effects.

Origin

Chatoyant moonstone material is sourced from key moonstone-producing regions in South Asia and Madagascar

Uses

Best for: Used in cabochons for jewellery and collector optical-effect stones.

Ideal uses: Cabochons oriented to maximize eye and sheen effects.

Care

Moderate hardness with cleavage; use protective settings and avoid impact.

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