gems, locality, species, chrome chalcedony, Zimbabwe, chromian chalcedony, mtorolite

This book presents a series of papers submitted to the Fifth Magmatic Sulphide Field Conference held in Zimbabwe, 3–13 August 1987, with the conference and ensuing publication representing the final acts of the IGCP project 161—which by virtue of the previous publications already attributed to this project must be considered highly successful. Virtually all the major protagonists one currently associates with magmatic sulphides were present at the meeting, where 27 papers were presented, 18 of which appear in this special publication. The initial three papers of the volume are devoted to the Great Dyke, and concern the geological background and mineralization, by Wilson and Prendergast, and new PGE data for the complex by Prendergast and Keays. Together these papers provide an excellent insight into current thought on the geology and mineralization of the Great Dyke, and incidentally serve as a testimony to the commitment of Martin Prendergast to the volume, co-author of three papers and editor! The following ten papers cover aspects of sulphide and PGE mineralization in the Madziwa Intrusion (Zimbabwe), the Bushveld Complex (South Africa), the Molopo Farms Complex (Botswana), the Rhana Layered Intrusion (Norway), the Duluth complex (U.S.A.), and the Lac des Iles and Montcalm complexes (Canada), as well as several mafic and ultramafic intrusions in Finland. These papers present a series of short articles which provide variable amounts of data—and although little significantly new data or theory emerges, they together present a useful dataset for those interested in magmatic sulphide deposits. The following three papers deal with the physical volcanism of Archaean komatiite-associated Ni deposits and their host rocks in the Yilgarn block, Western Australia. In one paper the concept of spinel non-stoichiometry and its effect on sulphide compositions is applied to chromitites in ophiolite complexes, and the final paper describes a gravity and magnetic survey of the Insizwa Intrusion in South Africa. In summary the volume is well produced, and has appeared approximately two years after the meeting—which seems about the norm these days. In my view, whilst the volume is certainly no ‘benchmark’ publication it nevertheless contains some interesting material for those concerned with researches or exploration activities related to magmatic sulphides, less so for the undergraduate and casual observer, but if nothing else further testimony, if any was required, of the success of IGCP project 163. S. Roberts