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Successful delivery of the United Nations sustainable development goals and implementation of the Paris Agreement requires technologies that utilize a wide range of minerals in vast quantities. Metal recycling and technological change will contribute to sustaining supply, but mining must continue and grow for the foreseeable future to ensure that such minerals remain available to industry. New links are needed between existing institutional frameworks to oversee responsible sourcing of minerals, trajectories for mineral exploration, environmental practices, and consumer awareness of the effects of consumption. Here we present, through analysis of a comprehensive set of data and demand forecasts, an interdisciplinary perspective on how best to ensure ecologically viable continuity of global mineral supply over the coming decades.

The iron oxide copper-gold (IOCG) group of deposits, initially defined following discovery of the giant Olympic Dam Cu-U-Au deposit, has progressively become too-embracing when associated deposits and potential end members or analogs are included. The broader group includes several low Ti iron oxideassociated deposits that include iron oxide (P-rich), iron oxide (F-and REE-rich), Fe or Cu-Au skarn, highgrade iron oxide-hosted Au ± Cu, carbonatite-hosted (Cu-, REE-, and F-rich), and IOCG sensu stricto deposits. Consideration of this broad group as a whole obscures the critical features of the IOCG sensu stricto deposits, such as their temporal distribution and tectonic environment, thus leading to difficulties in developing a robust exploration model.The IOCG sensu stricto deposits are magmatic-hydrothermal deposits that contain economic Cu and Au grades, are structurally controlled, commonly contain significant volumes of breccia, are commonly associated with presulfide sodic or sodic-calcic alteration, have alteration and/or brecciation zones on a large, commonly regional, scale relative to economic mineralization, have abundant low Ti iron oxides and/or iron silicates intimately associated with, but generally paragenetically older than, Fe-Cu sulfides, have LREE enrichment and low S sulfides (lack of abundant pyrite), lack widespread quartz veins or silicification, and show a clear temporal, but not close spatial, relationship to major magmatic intrusions. These intrusions, where identified, are commonly alkaline to subalkaline, mixed mafic (even ultramafic) to felsic in composition, with evidence for mantle derivation of at least the mafic end members of the suite. The giant size of many of the deposits and surrounding alteration zones, the highly saline ore fluids, and the available stable and radiogenic isotope data indicate release of deep, volatile-rich magmatic fluids through devolatization of causative, mantle-derived magmas and variable degrees of mixing of these magmatic fluids with other crustal fluids along regional-scale fluid flow paths.Precambrian deposits are the dominant members of the IOCG group in terms of both copper and gold resources. The 12 IOCG deposits with >100 tonnes (t) resources are located in intracratonic settings within about 100 km of the margins of Archean or Paleoproterozoic cratons or other lithospheric boundaries, and formed 100 to 200 m.y. after supercontinent assembly. Their tectonic setting at formation was most likely anorogenic, with magmatism and associated hydrothermal activity driven by mantle underplating and/or plumes. Limited amounts of partial melting of volatile-rich and possibly metal-enriched metasomatized early Precambrian subcontinental lithospheric mantle (SCLM), fertilized during earlier subduction, probably produced basic to ultrabasic magmas that melted overlying continental crust and mixed with resultant felsic melts, with devolatilization and some penecontemporaneous incorporation of other lower to middle crustal fluids to produce the IOCG deposits. Pre...

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The Big Gossan Cu-Au skarn deposit is the highest grade copper deposit in the world-class Ertsberg district, Irian Jaya. Current reserves are 37.4 million metric tons (Mr), grading 2.69 percent Cu, 1.02 g/t Au, and 16 g/t Ag. Mineralization is associated with a series of 3 to 4 Ma granodioritic dikes which have intruded close to the near-vertical faulted contact between the Shale Member of the Cretaceous Ekmai Formation and the stratigraphically overlying Paleocene Waripi and Eocene Faumai Formations. Most mineralization and alteration occurs in the purer carbonate rocks of the Waripi Formation, although biotite and calc-silicate hornfels alteration also occurs in the footwall rocks adjacent to mineralization.Prograde skarn alteration consists dominantly of pyroxene and garnet with an overall ratio of approximately 2:1. The average pyroxene and garnet compositions are Di73Hds4Joa and Ads47Gr•a5Sp•.sPy0..•, respectively. The skarn is zoned in three dimensions relative to the main fluid conduit along the Ekmai-Waripi contact. Proximal zones are garnet rich and the garnet has a dark red-brown color, whereas the pyroxene is pale in color and is iron poor. Intermediate zones contain subequal amounts of relatively coarse-grained, green pyroxene and brown garnet. Distal skarn zones are dominated by dark green, iron-rich (up to Hd75) pyroxene. Garnet in distal zones typically is pale green to greenish brown. At the skarn-marble contact, retrograde alteration (mostly amphibole and epidote) and sulfide minerals (mostly pyrite and pyrrhotite) are abundant. Chalcopyrite and anhydrite are present in all skarn zones. Although the skarn-marble contact is sharp, tiny dark veinlets (containing chlorite, serpentine, clay, sulfides, and/or carbon) which locally resemble stylolites record the passage of hydrothermal fluids for tens to hundreds of meters beyond the skarn. Skarn zonation in terms of mineral ratios, colors, and compositions can be used for exploration on both a local and district scale.In addition to mineralogy, Big Gossan is zoned with respect to metals. Cu, Au, Ag, Pb, Zn, As, and Co in the skarn all increase toward the top of the system, whereas Mo increases with depth. Similarly, Cu, Au, Ag, Pb, Zn, As, and Co increase (for a given elevation) toward the western and in most cases, toward the eastern margin of the system. Only Mo is inverse to this trend, defining a central core zone xvhich is interpreted to represent the main locus of fluid flow overlying the source pluton. Relative to the host rocks (Kembelangan and Waripi Formations), minera]ized skarn is enriched in Si, Fe, S, Cu, Ag, Au, As, Co, Se, and W. Both the host rocks and mineralized skarn are significantly depleted in rare earth elements relative to typical Phanerozoic sedimentary rocks. Particularly striking is the deep negative curopium anomaly, mostly < 1 ppm Eu.Fluids associated with prograde skarn are high-temperature, low COs (<0.05 mole %), NaC1-KC1 brines. Pressure-corrected temperatures for fluid inclusions in prograde skarn range from 360 ø to...

Abstract:The adequacy of mineral resources in light of population growth and rising standards of living has been a concern since the time of Malthus (1798), but many studies erroneously forecast impending peak production or exhaustion because they confuse reserves with "all there is". Reserves are formally defined as a subset of resources, and even current and potential resources are only a small subset of "all there is". Peak production or exhaustion cannot be modeled accurately from reserves. Using copper as an example, identified resources are twice as large as the amount projected to be needed through 2050. Estimates of yet-to-be discovered copper resources are up to 40-times more than currently-identified resources, amounts that could last for many centuries. Thus, forecasts of imminent peak production due to resource exhaustion in the next 20-30 years are not valid. Short-term supply problems may arise, however, and supply-chain disruptions are possible at any time due to natural disasters (earthquakes, tsunamis, hurricanes) or political complications. Needed to resolve these problems are education and exploration technology development, access to prospective terrain, better recycling and better accounting of externalities associated with production (pollution, loss of ecosystem services and water and energy use).

Rare earths, sometimes called the vitamins of modern materials, captured public attention when their prices increased more than tenfold in 2010 and 2011. As prices fell between 2011 and 2016, rare earths receded from public view, but less visibly, they became a major focus of innovative activity in companies, government laboratories, and universities. Geoscientists worked to better understand the resource base and improve our knowledge about mineral deposits that can be mines in the future. Process engineers carried out research that is making primary production and recycling more efficient. Materials scientists and engineers searched for substitutes that require fewer or no rare earths while providing properties comparable or superior to those of existing materials. As a result, even though global supply chains are not significantly different now than they were before the market disruption, the innovative activity motivated by the disruption will likely have far-reaching, if unpredictable, consequences for supply chains of rare earths in the future.