Gemstone Characteristics
Opal

Chemical Composition:
(Si O2 x H2O) Amorphous Silica Gel.
Hardness: 5.5 - 6.5
Refractive Index: 1.45
Specific Gravity: 2.1
Lustre: Sub-Vitreous to Resinous.
Locations Where Found:
Hungary, Australia, Mexico, Nevada.
Colours:
White, Black, Green, Pink, orange, Red.

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