. The Australian Museum magazine. Natural history. THE AUSTRALIAN MUSEUM MAGAZINE. 201 rock known as andesite, and is usually in small stones, though occasionally larger pieces have been found, and one preserved in the Vienna Museum is as large as a man's fist and has been valued at £3,500. WHITE CLIFFS. Australian opals have now almost ousted the European product from the world's markets. Precious opal was found filling cavities in the decomposed basalt of the Abercrombie Ranges, New South Wales, in the 'seventies, but Australian opal did not become impor- a sulphate of soda and lime, forming
. The Australian Museum magazine. Natural history. THE AUSTRALIAN MUSEUM MAGAZINE. 201 rock known as andesite, and is usually in small stones, though occasionally larger pieces have been found, and one preserved in the Vienna Museum is as large as a man's fist and has been valued at £3,500. WHITE CLIFFS. Australian opals have now almost ousted the European product from the world's markets. Precious opal was found filling cavities in the decomposed basalt of the Abercrombie Ranges, New South Wales, in the 'seventies, but Australian opal did not become impor- a sulphate of soda and lime, forming aggregates which from their appearance have been called fossil pineapples. Much of the opal found at White Cliffs has very little or no value for gem ]iurposes, and is known as ])otch, but the field has ]iroduced many fine stones. In valuing opal, several ])oints must be taken into account. Colour is the most im]>ortant, red fire, or red in combina- tion with blue, green, and yellow, being considered the best. Pattern is also an important factor. In pinfire opal the colour is in very small ])atches, almost pin points. Harlequin 0])al has the colour distributed in small, fairly regular Hm^- ,j»^^^' A-. ^ -«?. A Lightnins^ Ridge Opal Mine, showing the mouth of the shaft and the windlass by which the broken rock is hauled to the surface. [Photo.—y;r. J. V. Vaiiex tant until the White Cliffs field was o]>ened up. In 1889, a hunter was track- ing a wounded kangaroo in the drought stricken region beyond Wilcannia, and noticed a brilliantly coloured stone, which he picked up and retained as a curio. Other discoveries followed and soon the White Cliffs opal mines were in full swing. At White Cliffs the opal occurs in a white siliceous rock, a kind of sand- stone, of Cretaceous age, filling cracks and seams in the rock, or replacing the material of wood, shells, and reptilian bones. It also occurs as a replacement of a spikey mineral, probably glauberite. squares. In flash o
Size: 1602px × 1560px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectnaturalhistory, booky
