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Opals- So many Varieties

OPALS – There Are So Many Varieties

By Gary Hocking

It is no wonder that consumers do not know a lot about opals because they come from different regions in Australia and each region has a vastly different kind of opal.


How are opals formed?  In different ways and that makes them a little more confusing.


The most widely known opal has always been the white opal. Have a look at antique opal jewelry pieces and you are likely to find a reasonably colorless white stone.  Most of this stone came and still comes from South Australia.  It is also called light opal and it has a light or white colored background and through that background shines the opal play of color. This type of opal was formed in the center of Australia which was once an inland sea. Silica seeped into through layers of sandstone where it hardened and became opal.

Sometimes it seeped into cavities left by decayed and no longer existing sea shells and vegetation and the opal took on these shapes.


Then there is black opal and everyone who was used to seeing their grandmother’s white opal is simply stunned when they first see a good piece of Australian black opal with its magnificent play of colors.  Black opal has a black or dark gray background and through this the color bursts into life.  Black generally shows the colors off better than the white background.  Black opal is found in the state of NSW in a region known as Lightning Ridge. Black opal is considered superior to white opal, but that is not to say that white opal isn’t gorgeous and can’t be worth a fortune.  Black opal is formed the same way as white opal.


But then Boulder opal is formed differently to those two.  It is found in the state of Queensland and is found in an ironstone rock.  It looks like someone has melted colored glass onto a brown stone and it has stuck to it and run along the rock and achieved an undulating surface.  So boulder opal is left on this ironstone rock and most times the stone is cut in a free form shape, simply following the shape of the color. Boulder is exciting stuff when it is of high quality!


Then there is Yowah opal mostly known as Yowah nuts.  It is similar to boulder except that it is found inside a round, ball like piece of rock.


Then you will also hear of opal matrix.  This is where a boulder type of opal runs through the rock like veins of color.  The opal and the rock together are cut and polished.  Quite often the rock has tiny pin dots of speckled color running next to a rich flow of brilliant color.  This is also absolutely smashing stuff and often more reasonably priced than full opal.


There are also some very uncommon types of opals such as Hayalite which forms in volcanic rocks and is usually colorless.  There is also what is known as opal pineapples.  These are crystal clusters which are found in an area called White Cliffs in NSW.


Whatever type of opal you fancy will be cherished for generations to come and can be made into a unique piece of jewelry.


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