A. Merdith

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Australia produces over 90% of the world's precious opal from highly weathered Cretaceous sedimen-tary rocks within the Great Artesian Basin. Since opal was first discovered around 1870 until the present day, opal mining has been carried out by private operators working a claim no larger than 50 Â 50 m, usually in the direct vicinity of areas that have(More)
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