fiorite

Century Dictionary and Cyclopedia

1. n. A variety of silicious sinter found incrusting volcanic tufa. It is found in the vicinity of hot springs and volcanoes in globular, botryoidal, and stalactitic concretions with a pearly luster, and consists of silica (sometimes impure from the presence of alumina), iron peroxid, and water. Geyserite is a variety occurring about the orifices of geysers.

Wiktionary

1. n. mineralogy A variety of opal occurring in the cavities of volcanic tufa, in smooth and shining globular and botryoidal masses.

GNU Webster's 1913

1. n. (Min.) 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.