Iridescent Andradite Garnet | Gemopedia

Also called rainbow garnet, this gray to deep brown garnet displays phenomenal iridescence. The iridescence is caused by the way grossular and andradite garnet are mixed together in this single gem, forming a crystal structure that both scatters and traps light within the gem, creating a myriad of colors.

Iridescent Andradite Garnet Classification

Common Name

Iridescent Andradite Garnet

Species

Garnet

Variety

Iridescent Andradite Garnet

Colors

Alternate Names

Gemstone Groups

Group: Garnet

Key Separations

OTL RI, SG magnification and appearance

Comments

Rare stones might show chatoyancy.

Iridescent Andradite Garnet Optical Properties

Transparency

Semitransluscent To Opaque

Refractive Index

1.888

Birefringence

Optic Character

NA

Optic Sign

NA

Polariscope Reaction

singly refractive, commonly with ADR (SR-ADR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Dispersion

Strength: strong fire Value: 0.057

Comments

Iridescent Andradite Garnet Chemistry & Crystallography

Chemical Name

calcium iron silicate

Chemical Formula

Ca3Fe2(SiO4)3

Synthesis

Crystal System

Cubic

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Iridescent Andradite Garnet Characteristic Physical Properties

Hardness

6.5-7

Streak

white

Specific Gravity

3.81-3.87

Toughness

Fair To Good

Inclusions

Iridescent andradite garnet is type II clarity stone. Iridescence is caused by twinning planes and occurs in parallel angled bands or patchy areas.

Luster

Subadamantine To Vitreous

Stability

Fracture

Conchoidal To Uneven

Cleavage

None May Show Indistinct Parting

Comments

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