Boulder Opal is a unique and beautiful opal found in Queensland, Australia. It is easily identifiable because it is a mixture of ironstone and opal either in a matrix or layered. Every stone is unique and they are arguably the most affordable opal available.
This unique opal is spread over thousands miles and known as the Winton Formation, which is millions years old. Famous Boulder opal fields include Winton, Quilpie, Opal town, Jundah, Bulgaroo and Kyabra .
Koroit and Yowah are two opal fields close together and are now producing popular opal that has more pattern and unique style more than colour as most boulder opal fields.
We have now added these fields under Boulder opal as, many new buyers miss these categories. They have reputation for veins of colour in spectacular patterns compared to other Boulder opals fields
Koroit and Yowah generally have more dark chocolate ironstone backing and other opals fields have more sandstone light brown colour and both can display veins caramel colour.
Boulder opals have more variety and uniqueness compared to other opals and gemstones as so many factors have taking place over million years and different mineralization has helped in huge cross spectrum of unique boulder opals that you can enjoy
Another interesting type of Boulder Opal is the wood replacement fossil. These stones have replaced a cavity left over by old wood. This creates a stone with a unique wood pattern. Check them out, they are amazing.
Please note some colour bars on this opal is very thin and sometimes buyers mistake for doublet which is man made by joining crystal opal to ironstone
To check that it is genuine opal, best to have magnifying glass and view colour bar and you can see it isn’t glued by following colour veins. Also you may place in freezer for few minutes and if a doublet the glue would crystalize and easy to see
It is an extremely stable type of opal that does not generally crack or craze. Since it is mixed with ironstone it is very strong and resistant to breaking, but some boulder opals do show crack lines and most of these are caused when the opal was formed a s many times you will split open a boulder opal to see crack lines which could have been caused by shifts in the earth to earthquakes or movements when the opal was forming.