amorphous synthetic synthetic opal
Gilson Opal (Cabochon)
SiO2*nH2O
Quick Facts
Hardness
5.5
Specific Gravity
2.05
Refractive Index
1.44
Optical Character
Isotropic (amorphous)
Crystal Structure
amorphous
Physical Properties
Crystal Systemamorphous
Hardness (Mohs)5.5
Specific Gravity2.05
CleavageNone
FractureConchoidal
LustreVitreous to resinous
Optical Properties
Refractive Index1.44
Optical CharacterIsotropic (amorphous)
PhenomenonPlay of colour
FluorescenceVariable
Origin & Identification
Originsynthetic
Growth Methodgilson
ManufacturerGilson
First Produced1974
Diagnostic FeaturesLizard skin or chicken wire pattern under magnification, columnar structure visible from side, no potch (body colour layer), very regular play of colour, lower SG than natural
Colours
White opalBlack opalFire opal
Common Inclusions
Columnar structureLizard skin pattern
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Open in PlaygroundNatural Counterpart
The natural gem this synthetic imitates
Related Minerals
Other minerals in the amorphous system
