Abstract
Magmatic sulfide ore deposits are products of natural smelting: concentration of immiscible sulfide liquid (‘matte’), enriched in chalcophile elements, derived from silicate magmas (‘slags’). Sulfide ore deposits occupy a spectrum from accumulated pools of matte within small igneous intrusions or lava flows, mined primarily for Ni and Cu, to stratiform layers of weakly disseminated sulfides within large mafic–ultramafic intrusions, mined for platinum-group elements. One of the world's most valuable deposits, the Platreef in the Bushveld Complex (South Africa) has aspects of both of these end members. Natural matte compositions vary widely between and within deposits, and these compositions are controlled largely by the relative volumes of matte and slag that interact with one another.
Highlights
By the same process that has been used since prehistoric times to extract metals from ores, magmatic sulfide ores form by the interaction between immiscible sulfide-oxide liquids with silicate magmas
They fall into two major categories: sulfide-rich, exploited primarily for Ni and Cu; and sulfide-poor where the dominant value is in the platinum-group elements (PGE) and Au
Almost all unaltered magmatic sulfide ores, regardless of sulfide mode, have a characteristic assemblage of pyrrhotite-pentlandite-chalcopyrite-platinum-group minerals (PGM); an assemblage formed from the cooling and crystallization of a magmatic-derived sulfide matte
Summary
Stratiform accumulations of a few percent of disseminated sulfide in cumulates within large layered mafic-ultramafic intrusions, including PGE-enriched “reefs” (Naldrett et al 2008) Such deposits are typically exploited for PGEs with byproduct Ni, Cu and Co. Such deposits are typically exploited for PGEs with byproduct Ni, Cu and Co They generally occur as remarkably thin and persistent layers: the best-known example, the Merensky Reef of the Bushveld Complex (Figure 1C) is commonly only a few tens of cm thick but extends continuously for over 400 km. There is evidence of thermal or thermomechanical erosion, in the form of transgressive footwall troughs beneath komatiite flows (Fig. 2A), or in “chonoliths” (Fig. 2D,E) that truncate layering within the country rock and often contain partially digested wall rock fragments Such host bodies are usually very small compared to the total volume of magmatism in the province: in the case of the ore-hosting intrusions of the Norilsk-Talnakh camp, about 1 millionth of the total volume of the Siberian Trap lavas
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
