BOULDER OPAL SLAB 2
A rare rough Queensland Boulder Opal Slab 2. You almost never get unworked pieces like this for sale. Really this is a gem in the rough. Features ethereal streaks of colour on a white background, wrapped in its sandstone host rock. I’ve done my best but it does look so much better in person. Polished up of course it will look absolutely stunning. A great project for the lapidary or opal enthusiast or jeweller or it could be for a collection. A super piece!
Location:
Queensland.
Dimensions:
5.8cm x 3.8cm x 0.7cm, 26g.
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.