Fiorite is a hydrated silica mineraloid, a form of opal, found in cavities in volcanic tuff.
It is a globular, botryoidal, or stalactic concretionary form of opal.
The mineraloid has a pearly lustre and forms botryoidal masses.
Named after Santa Fiora, Italy, fiorite is used as a gemstone.
This article about a specific mineral or mineraloid is a stub.