amorphous composite assembled stone
Opal Triplet (Cabochon)
SiO2*nH2O between dome cap and dark backing
Quick Facts
Hardness
5.5
Specific Gravity
1.9
Refractive Index
1.44
Optical Character
Isotropic
Crystal Structure
amorphous
Physical Properties
Crystal Systemamorphous
Hardness (Mohs)5.5
Specific Gravity1.9
LustreVitreous (glass-like from dome cap)
Optical Properties
Refractive Index1.44
Optical CharacterIsotropic
PhenomenonPlay of colour
Origin & Identification
Origincomposite
Diagnostic FeaturesThree-layer construction visible from side, dome cap (quartz or glass) creates glassy appearance, flat back with dark backing, play of colour may appear slightly muted under dome, cannot be immersed (adhesive dissolves)
Colours
Black opal appearanceVarious play of colour
Common Inclusions
Three-layer constructionDome capJunction planesDark backing
Interactive Preview
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Open in PlaygroundNatural Counterpart
The natural gem this composite imitates
Related Minerals
Other minerals in the amorphous system
