| Abstract: | SUMMARIES. An elephant tusk fragment, excavated from the wreck site of a seventeenth-century Dutch trading vessel, has been analysed to determine the impact of prolonged immersion in a marine environment on this object. Samples taken from different parts of the fragment were analysed using inductively coupled plasma atomic emission spectrometry, automated powder X-ray diffraction, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. These analyses demonstrated that most of the collagen has been lost from the ivory and that there has also been significant alteration of the inorganic matrix. Interestingly, it appears that there is greater retention of collagen in the outer parts of the tusk fragment than in the core. Conversely, the inorganic material is better preserved in the core. Changes in chemical composition and in the relative proportions of components were determined. In addition to providing information about the nature and extent of deterioration of ivory in a marine environment, the work undertaken has allowed an appreciation to be gained of the relative merits of these analytical techniques when applied to waterlogged, archaeological ivory.
CONCLUSION. The tusk fragment GT 993. which was immersed for about 320 years in a marine environment, is in a markedly worse condition than the 1000-year-old bones which were also recovered from a marine environment and examined by Arnaud and his co-workers [22]. The differing conditions of these materials highlights the need for characterization not only of the objects themselves but also of the environments from which they were recovered. If such characterizations are made, and relationships are established between the burial environment, the period of immersion and the extent of diagenetic change, then the understandings gained should lead to the development of a more systematic approach to the treatment of waterlogged ivory. |
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