Australian opal gemstones how rare are they?

by Kevin Sorrell

Did you know that nearly all opals 80% come from Australia, there are some opals which are very valuable and a lot that are not. The Black opal which is only found in Lightning Ridge New South Wales is the most valuable. pickaxe Anyone can mine for opal all you need is a 1. A steel picket or wooden post(at least 75mm thick) 2. Trenches(1metre long and 150mm deep) 3. "Possession notice" displayed 4. Claim must be square in shape and may not exceed 50 x 50 metres 5. A MINERAL CLAIM

More information about this can be found here http://www.wj.com.au/mining/claim.html This is something that, id like to do myself one of these days. The types of opal

black-opalBlack opal is most valuable, it is very rare to find, even more rare than diamonds, black opal has blue and green color, sometimes red which makes it very valuable, black opal is technically a form of dark opal, where the background color is black, rather than brown all forms are black opal. Boulder opal

boulder-opalis second most valuable, its is found in iron stone mainly only mined with in large open cut mines, blue or sapphire color is the prominent color although can show sign of red color which again increases the value, Boulder opal is mainly found in Queensland in outback towns like Quilpie and Winton. Light opal

light-opalcan vary from grey to clear, but most common gem grade is white, milky opal, semi opaque white, as with all opals, all the colors of the rainbow may show, due to the light background color, the flash may not show as strong as with some other opal types, Coober Pedy Australia is the main source of light opal. Crystal opal

opal-crystalis a form of light or black opal where the background color is transparent, Andamooka in South Australia is the place to find some of the best crystal opals, fossils that contain opal in them as well. Matrix Opal

matrix-opalThe term matrix opal is used where the opal is intimately diffused in rock which it was formed, Andamooka matrix opal is a porous opal from Andamooka, South Australia, which might be treated to enhance the colour by depositing black carbon by chemical treatment in the pore spaces in the stone. How is a opal made or formed

cretaceous-period-australiaDuring the Cretaceous period of time 65 - 140 million years ago Southern Australia was covered by sea, this is when opal started to form from a gel like silica or very fine sand that ( this is what silicon chips for computers is made from ) and over time trapped in pockets and crevices over millions of years under hard packed sandy rocks. Opal is a lot different than most gem stones as they are not a crystal but more like a silica glass, potch a common opal that is mostly used for inserts for table tops, guitars, ashtrays and cheap jewelry, sometimes you might find good or rare opal under or in the potch, potch is a very common opal, some people find great veins of this where black opal is located. Where can you find Opals ?

Opal is found in lots of places in Australia South Australia, New South Wales and Queensland.

Coober Pedy in South Australia. Opal found here is white to light color, houses and the local pubs here are mostly underground dwelling's.

Lightning Ridge in central New South Wales, Lightning Ridge mines the best quality rare black opal in the world. In addition to opal, Lightning Ridge you can find fossil opal, many people come here to mine for opals.

Queensland , a town called Quilpie and Winton in the north is where boulder opal is found, it is not as rare as black opal, but its still valuable, most of the opal here is mined in traditional underground mines, Queensland boulder opal is also mined using bulldozers to open cut through the mine field, it is not a very nice place to visit, but if your after opals then who cares what the location looks like.

Source: http://www.goarticles.com/cgi-bin/showa.cgi?C=1545554