BOULDER OPAL SPECIMEN
A beautiful natural Boulder Opal Specimen 2. Photos of this Opal were taken outside. It would be a beaut gift for someone special. The Iron Oxide showing bright orange looks great in contrast with the Opal.
4.1cm x 3.1cm x 2.3cm, 48g.
nH2O Hydrated Silicon Dioxide.
Opal has been a popular gem for many centuries and has a very interesting structure. The name opal comes from the Sanskrit name for precious stone upala. Opal structure is not crystalline and considered a mineraloid. The chemistry of Opal is primarily SiO2 and varying amounts of water. The amount of water varies from 5 -10% and greater. This water can help geologists determine the temperature of the host rock at the time the opal formed.