Meaning of opal | Babel Free
Definitions
A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula SiO₂·nH₂O.
CEFR level
B1
Intermediate
This word is part of the CEFR B1 vocabulary — intermediate level.
This word is part of the CEFR B1 vocabulary — intermediate level.
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