The symposium on magmatic ore deposits was a well balanced program. Thirteen papers on oxide ores were presented, two of which were the result of experimental laboratory work. Nine papers on magmatic sulfides were read, two of which were also the result of experimental laboratory work.
The symposium has confirmed the concept of the separation and emplacement of mineral products from a fluid magma. It would appear from the evidence that the case for oxide ores is better and more secure than the case for sulfide ores. The former results in a more orderly progression in the reaction products during the crystallization of the magma. This is not so readily apparent in the case of sulfide ores. For example, the sulfides in the Bushveld occur mainly in the Merensky Reef and in the Vlakfontein pipes, neither of which are at the base of the irruptive. At Sudbury and Muskox the sulfides occur at the base of both, but appear to have arrived there by different mechanisms. The sulfide deposits as we know them appear to have been subject to more variance and have produced a greater variety of results all stemming from a seemingly common set of conditions. Perhaps with more work we will be able to rationalize these mechanisms. This now seems to be the problem concerning us rather than the question of whether or not the process of magmatic separation is or is not valid.
Figures & Tables
Magmatic Ore Deposits
This monograph on Magmatic Ore Deposits has resulted from a Symposium held at Stanford University on November 12 and 13, 1966. All except three of the papers that were presented are published in this volume as well as some of the discussion and the summation of the symposium. Unfortunately much of the discussion cannot be included because the volume is already so large. The best introduction to this volume is, perhaps, the introduction as it was presented at the symposium:
This symposium was conceived in 1962 when the Program Policy Committee recommended that the . Society of Economic Geologists should sponsor a symposium on magmatic ore deposits. The Committee under the chairmanship of John K. Gustafson believed this to be an effective method of advancing geologic thought. It is fitting that the symposium should finally be held during Gustafson’s presidential year. The proposal of the Program Policy Committee was approved by Council at its meeting in November, 1962. A special committee consisting of G. Kullerud, J. A. Noble, C. H. Smith, T. P. Thayer, with H. D. B. Wilson as chairman, was appointed by the President, Olaf N. Rove, in February 1963 to make arrangements for the symposium. E. N. Cameron, Secretary of the Society, was ex officio member of the special committee and remained as an active member when he resigned the secretaryship. C. H. Park, Jr. joined the committee shortly after its formation.
The Program Policy Committee was prompted to recommend the symposium by the realization that the underlying theory of the formation of magmatic ore deposits was formulated many decades ago., In the intervening years, much new data have been acquired from systematic research. It seemed to the Program Policy Committee that it was time for those with an abiding interest in the magmatic deposits to meet to assess this new data and to point out the unresolved problems.
The symposium was entitled “Symposium on Magmatic Ore Deposits.” The special committee accepted the terminology in the “Glossary of Geology and Related Sciences,” Edition 2, page 175.
Magmatic Deposits Certain kinds of mineral deposits form integral parts of igneous rock masses and permit the inference that they have originated, in their present form, by processes of differentiation and cooling in molten magmas. (Lindgren p. 863, 1929).
The symposium committee has added the term “ore” to attempt to keep the discussions centered on ore, or near ore material, or with