Andradite Garnet (Cat's-Eye) | Gemopedia

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case andradite garnet. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line. Andradite garnet is relatively unfamiliar to the general public, but this species includes demantoid, melanite, topazolite and schorlomite. Garnets that feature a cat's eye are a rare occurrence and should be treasured.
Colors
Yellow Green To Brownish Orange

Andradite Garnet (Cat's-Eye) Classification

Common Name

Andradite Garnet (Cat's-Eye)

Species

Andradite

Variety

Cat's-Eye Andradite Garnet

Colors

Yellow Green To Brownish Orange

Alternate Names

Gemstone Groups

Garnet

Key Separations

OTL RI, spectrum and SG

Comments

Andradite Garnet (Cat's-Eye) Optical Properties

Transparency

SemiTranslucent To Opaque

Refractive Index

1.888

Birefringence

Optic Character

NA

Optic Sign

NA

Polariscope Reaction

Singly Refractive (SR) With ADR

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

None

Dispersion

Strength: strong fire Value: 0.057

Comments

Andradite Garnet (Cat's-Eye) Chemistry & Crystallography

Chemical Name

calcium iron silicate

Chemical Formula

Ca3Fe2(SiO4)3

Synthesis

Crystal System

Cubic

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline to Aggregate

Comments

Andradite Garnet (Cat's-Eye) Characteristic Physical Properties

Hardness

6.5-7

Streak

Specific Gravity

3.81-3.87 Typical: 3.84

Toughness

Good

Inclusions

Iridescent andradite garnet is type II clarity stone. Chatoyancy is caused by parallel needles. Due to the stones low mohs hardness it might have scratches and abrasions.

Luster

SubAdamantine

Stability

Fracture

Conchoidal, Uneven

Cleavage

None

Comments

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