Opal Mystery
For ages people have been believing in the healing power of Opal. It is reported to be able to solve depressions and to help its wearer find the true and real love. Opals are supposed to further enhance the positive characteristics for people born under the zodiac sign of Cancer. Black Opal is recommended to those born under Scorpio, and Boulder Opal is the lucky stone for Aries. The fantastic colour play of Opal reflects changing emotions and moods of people. Fire and water, the sparkling images of Boulder Opal, the vivid light flashes of Black Opal or the soft shine of Milk Opal – striking contrasts characterise the colourful world of this fascinating gemstone. Maybe this is the reason why it depends on our daily mood which Opal we prefer. Opals are like human emotions: you always experience them different and anew.
Boulder opal is unique to Queensland. It occurs in deposits in weathered sedimentary Cretaceous rocks in the west of the state. It is found in siliceous ironstone concretions or boulders ranging in size from less than a few centimetres to more than 20 cm. Concretions up to 5 cm across, known as ‘nuts’, may host a kernel of solid opal or contain a network of thin veins of opal through the ironstone. This variety of opal is prevalent at Yowah where the concretions form distinct bands—the well known ‘Yowah-nuts’. Matrix opal Only a small proportion of boulders contain precious opal. Others contain matrix opal. In these,the opal occurs as an infilling of pores or holes or between grains of the host rock (ironstone). Varieties of boulder opals are defined by body tone, play-of-colour and transparency. They include black, dark and light variations. Occurrences Queensland’s opal fields are the west and south-west of the state. They include: Yowah field (the southernmost field centred on the small town of Yowah—includes Black Gate) Koroit field (north-east of Yowah) Toompine field (east and south-east of Toompine—includes Lushingtons, Coparella, Duck Creek, Sheep Station Creek and Emu Creek) Quilpie field (west and north north-west of Quilpie—includes some of the more productive mines in recent times—Pinkilla, Bull Creek, Harlequin, and probably the most famous of all, the Hayricks. Kyabra–Eromanga field (west and north-west of Eromanga) Bulgroo field (north of Quilpie field in the Cheviot Range—includes the Bulgroo, or Germans—and Budgerigar to the north ) Yaraka field—includes the mines in the Macedon Range, such as Mount Tighe Jundah field (west of Jundah over the Thompson River—includes Jundah and Opalville mines) Opalton–Mayneside field (centred on the old abandoned township of Opalton, and to the south in the Horse Creek – Mount Vergemont area) Kynuna field—the most northerly field, south of the township of Kynuna.