Volume 24, Number
8, October - December 2011
Jack Townsend Memorial Issue
 Front cover image: Harp made from Cowell nephrite jade, black with a touch of very dark green, and hand engraved Sterling Silver fittings including 144 tuning keys and strings. 1500 hours work completed in 1984 by Albert Van Dijk. Photo by Rodney Harris. The Virgin Rainbow opal. |
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(Follow this link for abstracts of past issues)
Gemstone - microphotography images
William F. Ashford
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ABSTRACT |
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Jack's Opal
Ronnie
Bauer
 The finished product. The cleaned stone with Jack Townsend etched into the opal. |
ABSTRACT In this paper I will share with readers the process that we have developed to laser cabochon cut gems using a solid white opal from Andamooka as the test sample |
Jack,
opal specialist valuer
Nicholas
Kollias
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ABSTRACT Jack and I were approved opal specialist valuers for the Australian Government’s Cultural Gifts Program. In the last few years, we were in the very privileged position to examine some of the rarest and most significant opals that have ever been unearthed. The last valuation that Jack completed for the SA Museum was that of arguably, the finest opal ever unearthed: The Virgin Rainbow, an opalised Belemnite pipe. |
 The Virgin Rainbow - Opalized Belemnite pipe, measuring 63.3mm x 13.3 - 14.3mm, weighing 72.64 carats, found at Brown's Folly, 23 Mile, Coober Pedy, Australia. |
Diamonds and opal
Brian J. Morris
 Jack next to a kimberlite dyke near Terowie. |
ABSTRACT Jack Townsend (“Gemstone Jack”) was a colleague at the Geological Survey of South Australia for many years and we worked together on several projects particularly diamonds and opals. We undertook numerous rewarding field trips around Terowie and Orroroo, in the State’s mid north, in the search for kimberlites and were successful in locating several new occurrences. |
Tourmaline from Kangaroo Island, South Australia, in the Australian Museum collection
Gayle Webb
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ABSTRACT During most of Australia’s history of European settlement, the only known source of gem tourmaline (elbaite) was Kangaroo Island, an island off the coast of South Australia. An isolated place with magnificent scenery, abundant wildlife (the name is appropriate) and a few small hamlets, it is not an area one would immediately associate with mining. Yet its ancient rocks have yielded a variety of gemstones. |
 Blue tourmaline from Kangaroo Island, SA, 14.62 ct. Photo by Stuart Humphreys, Australian Museum. Specimen Australian Museum, Sydney. |
Luminescence of gem opals: a review of intrinsic and extrinsic emission
Eloise Gaïllou, Emmanuel Fritsch and Florian Massuyeau
 Orange luminescing opal (quincyite variety) from France in LWUV. |
ABSTRACT The luminescence of opals (SiO2, nH2O) is quite variable, as many opals fluoresce under ultraviolet radiation, while others are inert. Often the fluorescence of play-of-colour gems is described as chalky white to blue to yellow, whereas green is often seen in common opal. Orange is strictly restricted to pink body-colour opals. We propose a review of this phenomenon based on some published data and essentially on recent work. |
Less frequently encountered gemstones - Kyanite
Rod Brightman
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ABSTRACT Kyanite is better known as a bluish green mineral that has interesting directional hardness properties. In recent years a number of new finds have produced kyanite in gemmy forms and in a number of intense colours and cat’s-eye forms. Despite its differing hardness and perfect cleavage, it is now frequently encountered in collections of less common gemstones and is readily obtainable at most larger gem and mineral shows. It is also hard enough to be worn with care in jewellery. |
 Orange kyanite – 0.60 ct ( |
