Black Opal
gem · rare
Quick facts
- Formula
- SiO2·nH2O
- Hardness
- 5.5–6.5
- Luster
- vitreous
- Colors
- various with play-of-color
Black opal is the rarest and most valuable type of opal, known for its dark body tone and vibrant play-of-color.
Identify by its dark body tone and bright play-of-color without a visible matrix.
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