BOULDER OPAL SPECIMEN
A beautiful natural Boulder Opal Specimen. This Opal looks more purple than blue to the eye, the camera seems to have picked up on the blue more. We call this colour blurple! This is a super little piece of Opal in the rough. Photos of this Opal were all taken outside, many with the rock wet. This shows how the Opal would look if polished. It would be suitable for cutting, display or as a beaut gift for someone special this Christmas.
5.9cm x 4.4cm x 4.9cm, 206g.
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 considered 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.