BOULDER OPAL SPECIMEN
A beautiful natural Boulder Opal Specimen. This Opal looks great with good translucency and colouring. This is a super little piece of Opal in the rough. Photos of this Opal were all taken outside. It would be suitable for cutting, display or as a beaut gift for someone special this Christmas.
Location:
Queensland.
Dimensions:
6.6cm x 4.6cm x 3cm, 78g.
Opal: SiO2 · nH2O
Hydrated Silicon Dioxide.
Boulder Opal is a variety of Precious Opal. Found in Queensland, Australia, as cracks or coatings in and around ironstone/sandstone boulders. Opal has been a popular gem for many centuries and has a very interesting structure.
Opal is a mineraloid because this structure is not truly crystalline. 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.