Fiorite is a hydrated silica mineraloid, a form of opal, found in cavities in volcanic tuff<!--NOT tufa-->. 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.
See also
- Geyserite
References
- Mindat with location data