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THE AUSTRALIAN MUSEUM MAGAZINE. 





An opal miner's residence at Liglitning Ridge. 



[Photo. — Dr. J. V. Danes. 



At Lightning Ridge the mode of 

 ■occurrence of the opal is the same as at 

 White Cliffs, namely in a white, pow- 

 dery, siliceous rock, through which it is 

 scattered in an irregular manner. 

 There are practically no surface indica- 

 tions to guide the prospector, who must 

 just hope for the best. Many of the 

 miners work for a long period, perhaps 

 months, with little or no reward, others 

 may make a valuable " strike " in a 

 few days. This lends a fascination to 

 the search, for even the novice may 

 cherish hopes of encountering a rich 

 patch, if not to-day, then to-morrow. 

 No great skill or experience is required, 

 just strong arms, a stout heart and an 

 0])timistic outlook. The miners gener- 

 ally work in small parties of two, or 

 three, or four, pick their claim as close 

 as possible to one which is known to be 

 payable, sink a shaft perhaps to a 

 depth of from forty to a hundred feet, 

 and then drive tunnels outwards 

 through the rock in search of the 

 elusive gem. 



QUEENSLAND OPAL. 



In Queensland some fine opal has 

 been found widely distributed over the 

 south-west, as at Barcoo Creek, Opal- 

 ton, Yowah, Jundah, and other places. 

 It occurs in the so-called Desert Sand- 

 stone, frequently as the nucleus of large 

 ironstone nodules. 



STUART RANGE OPAL FIELD. 



This, the newest opal field, was 

 discovered about 1915. Stuart Range, 

 about ninety miles west from William 

 Creek station, on the northern railway 

 line. South Australia, forms the divide 

 separating a lake with the handy name 

 of Cadibarrawirracanna from that con- 

 taining Lakes Woorong, Phillipson, and 

 Wirrida. These "" lakes " are usualh^ 

 mere clay pans, holding water only for 

 a short time after rain has fallen (which 

 is seldom). 



The mode of occurrence of o])al at 

 Stuart Range is strikingly similar to 

 that of the o])al of New South Wales 

 and Queensland, for it is found in 

 irregular veins and patches enclosed in 

 sandstone and claystone of Cretaceous 

 age, and also replacing the remains of 

 fossils. The method of working at 

 Stuart Range is very simple, a pocket 

 knife being sometimes the prospector's 

 only tool. The soil is carefully worked 

 over in search of fragments of bleached 

 opal, which are followed till the seam is 

 found, then the opal is carefully ex- 

 tracted and trimmed with pliers. 



In all the Australian opal fields the 

 miner's bugbear is scarcity of water, 

 for it is only in the dry country, with an 

 annual rainfall of not more than fifteen 

 or sixteen inches, that the rainbow gem 

 is found. And this is probably no 

 mere accident, for it seems prob- 



