A thematic session on the use of stable isotopes in the study of mineral deposits was held as part of the annual meeting of the Mineral Deposits Studies Group in Newcastle upon Tyne on 14th December 1987. Five of the papers presented at the meeting are published here, together with abstracts for six other contributions.
The thematic session consisted of 15 papers, with invited contributions from D. T. Rickard and S. M. F. Sheppard. In order of presentation, S. H. Bottrell (University of Leeds) discussed the results of a stable isotope study of the Dolgellau black shale hosted gold mineralization, and demonstrated that the ore fluids were probably derived from an external igneous source, with considerable modification of isotope ratios by interaction with the host rock. P. Eakin (Queen's University of Belfast) then examined evidence for 13C isotopic fractionation as a consequence of radioactivity within uraniferous hydrocarbons, comparing data for samples from the North Wales orefield with others from Scandinavia and South Africa. This study showed that fractionation effects in excess of 10% may be caused by this process, requiring caution when interpreting C isotope data for organic matter from uraniferous mineral deposits. The following two contributions introduced two recently developed techniques to those within the audience who were not specialist isotope geochemists. S. P. Kelley (with A. J. Boyce, A. E. Fallick, P. J. Hamilton and R. M. McIntyre; SURRC, East Kilbride) described the use of laser microprobe extraction techniques which allow small samples to be studied without the