Australian Boulder Opal, a large specimen from Queensland
This is lovely piece of Australian Boulder Opal from Queensland. It measures 10cm x 8cm and weighs 400gm, with typical colour. Although the colour is not vivid are still attractive and typical of this iconic stone. This large piece of boulder opal in a attractive shape, this would be an impressive addition to anyones mineral or crystal collection.
Boulder opal generally occurs in large ironstone boulders. Millions of years ago silica rich water was able to permeate into cracks and fissures within these rocks. The very highest grade boulder opal can be incredibly expensive, ‘Black Opal’ being the most valuable. The first discoveries of boulder opal were about 150 years ago in Western Queensland near Quilpie. The mines operated today in Queensland are mostly small scale family affairs with the mine shafts between 5 to 25 metres deep. When Boulder Opal is used for jewellery it is always cut into cabochons. The gorgeous colours of the ironstone make a wonderful contrast to the colours of the opal. Some of the more well known opal fields in Queensland include, Opal Town, Quilpie, Jundah, and also Winton. Although other countries produce Opal, the vast majority originates from Australia.