Australian Opal Rough

The rough opal that comes from Australia is not far different from the opal that comes from other areas in the world. There is one field in Australia that produces a one of a kind opal type that nowhere else in the world and that is black Nobby opal from Lightning Ridge.

Nobby opal is a mysterious form of opal from Australia that forms underground in cavities that are rounded in shape, not flat like seam opal. The idea of how nobby opal is formed goes something like this.

There are clay balls sitting in cavities underground where the high traces of silica beads are, and the water from the rain seaps through the ground, washing the clay balls around and around until they are ground away by friction. This leaves a cavity that eventually fills up by silica spheres carried by the seeping water. As the rain falls many many times over the years, the silica forms layers of opal. Some rains will form common or black potch, and then you will get one layer of silica spheres that are stacked evenly. This has just formed precious opal or what we call opal with color and pattern.
We then have a cavity undergound filled with silica or opal that is a perfect black opal. (not all opal nobby’s form like this but when a perfect opal if formed this is what happens).

Australian opal rough also comes in a seam opal form that is also found in and around Lightning Ridge, but down in South Australia in Coober Pedy, we have a seam opal that is very bright in color but mostly only comes in a crystal opal form.

The seam opal forms in fissures and cavities underground that have been opened by movements in the fault lines. When a fault line has been pushed up or sideways, the fault will usually hit another block of ground. With immence pressure the cavities can form underground these are called fissures.

The same process happens as the ground that is rich in silica spheres get washed by the rain seeping through the ground carries the silica spheres into the cavities form opal over millions of years.

There are some theories that opal only takes a few hundred years but that is yet to be proven.

Most of the world supply of opal is mined in Australia and 98% of the world black opal is mined in Lightning Ridge.

We have an ancient inland sea that all the opal fields are edged on the shores of where the sea used to be, millions of years ago.

Some Australian opal is formed as volcanic opal, like a place called Tintenbar. This type of opal is very unstable and usually will crack up in a few days or weeks. Nobody mines there because of the opals vulnerability.

Every continent has some form of opal silica but only very few countries have opal with gem color and pattern. Australia would have to be the best place in the world to come and visit opal-mining fields.

For more information on opal cutting or purchasing opal. Please email blackopalsdirect@live.com or you can call me on Skype My username is Blackopaldirect and it's free!

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Australian opal jewelry - Lightning Ridge - Australian opal rough - Free form opal - Opal Chips - Australian Opal Cutters - Rough Australian Opal - Rare Opal - Unset Opal - Opal Cutting - Man Opal Ring - Black Opal Jewelry - Opal Gemstones - Loose Opals - Rough Opals - Australian Boulder Opal - Australian Opal

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