World Of Gems Conference 2017 Proceedings Book

WORLD OF GEMS CONFERENCE V - 41 - SEPTEMBER 2017 I n the 21 st century we tend to think that there are few to- tally unknowns in the field of gemmology. There is one group of gemstones however, about which we know al- most nothing – the Jet Group. Jet, a symbol of status within society since the Neolithic, has a strong cultural and historical importance to those people who work it. Indigenous jet working communities can still be found in Europe, Asia and the Americas but sadly, a lack of research allows both natural and synthetic simulants to threaten the heritage and cultural identity associated with the jet working way of life. Time is running out to protect the jet craftsmen. Appellation of origin is essential to preserve this, the oldest gemstone industry on earth. From a gemmological perspective, jet testing is problematic. Our go-to gem testing methods are inconclusive with regards to the identification of jet, and although coal petrology gives us a basic understanding of the nature of jet, it also fails to gives us appellation of origin. Added to these issues, the word ‘jet’ has become a generic term to cover a whole range of ma- terials which are used for jewellery purposes. As a result, members of the jewellery trade struggle to distinguishWhitby Jet from the many Victorian simulants, particularly problematic due to their similarity in appearance and handling. My aim is to gain a better understanding of the geological processes responsible for the formation of jet, and to establish which mechanisms are controlling the quality of jet from a gem- mological perspective. I intend to create a database of the quan- tifiable gemmological properties of the jet from each geograph- ical location, which, coupled with geochemical data, will provide a tool for trading standard authorities to protect jet working com- munities. I plan to expand on the Particle Induced X-ray and Gamma Emission Spectroscopy (PIXE,PIGE) I started in con- junction with The National Museum of Scotland (2016). Iron Mössbauer Spectroscopy (FeMS) and Laser-induced Break- down Spectroscopy (LIBS) will hopefully build on our initial re- sults which indicated that geochemistry varies not only between jet samples from the same geographical location, but also within individual jet samples suggesting a low level of chemically ho- mogeneity.The extent of the role of paleo-redox conditions and original biological precursors must also be evaluated, as must the unique polymeric and electrical properties of jet. As a gemmologist, but more importantly a jet lapidary, I find myself in a unique position to make a difference, not only from a scientific perspective but more importantly also on a human level. u REFERENCE Steele S.C., 2016 Advanced Jet Testing. Gems & Jewellery, Vol 25/No.5. p.22-25, Gem-A Publications. ACKNOWLEDGMENTS Dr Alison Sheridan and Dr Lore Troelen, The Nation Muse- ums of Scotland. The funding for PIGE was provided by the Integrated Platform for the European Research Infrastructure on Cultural Heritage. THE JET GROUP Sarah Caldwell Steele, FGA, DGA THE JET GROUP POSTER ABSTRACT FIGURE 1. (clockwise from bottom left) samples of Whitby, Siberian, Asturian, Mongolian, Georgian Republic (and centre) Turkish Jet. FIGURE 2. Jet from the Georgian Republic. Currently the greatest threat to indigenous jet industries. FIGURE 3. (clockwise from top left) Bois Durci, French Jet, Whitby Jet, Pressed Horn, Pique, Bakelite, Bog Oak, Vaux- hall Glass and (centre) Vulcanite.