01 n. A variety of opal occuring in the cavities of volcanic tufa, in smooth and shining globular and botryoidal masses, having a pearly luster; …
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1.
A variety of opal occuring in the cavities of volcanic tufa, in smooth and shining globular and botryoidal masses, having a pearly luster; -- so called from Fiora, in Ischia.(Min.)