Opal from Querétaro, Mexico: fluid inclusion study
The distinctive orange-to-red “fire" opals from Querétaro have not been found in significant quantities at any other locality.
New occurrence of fire opal from Bemia, Madagascar
Twenty-two gem opals from a new volcanic deposit located near Bemia
Opal from Queretaro, Mexico: Occurrence and Inclusions
An examination of play-of-colour opal from Mexico and its variety of inclusions.