GLOBAL COPPER RESOURCES AND RESERVES; DISCOVERY IS NOT THE ONLY CONTROL ON SUPPLY

Copper (Cu) is vital to modern life and has an often irreplaceable role in everyday infrastructure and technology. However, although clearly the world’s endowment of extractable Cu is finite, global Cu production has increased over the past century, an increase that has been (more than) matched by significant growth in estimated Cu mineral reserves and mineral resources. Globally, some 2,301 deposits contain reported Cu resources, split into 1,271 code-based (e.g. JORC, NI43-101) and 1,030 non-code-based resources. A further 393 deposits have both resources and code-based reserves and a further 14 deposits have non-code-based reserves. These deposits contain 3,034.7 Mt of Cu, up from the 1,861.3 Mt of Cu contained in global resources in 2010, including 640.9 Mt of contained Cu in reserves. These figures should also be considered a minimum given the lack of reporting of Cu resources from some countries and projects. Most mineral deposit types have also recorded an average increase in Cu resources between 2010 (Mudd et al., 2013) and 2015, although grades are often similar, slightly lower (by ~5%), or are significantly lower depending on mineral deposit type.

Porphyry deposits still dominate global Cu resources and reserves and host ~75% of the contained Cu in our database. Chile also dominates global Cu resources and reserves, followed by the USA and Peru, all which host copper resources and reserves dominated by porphyry systems, indicating the continued importance of this deposit type for global copper production (as well as Mo, Re, Au, and others). The increase in global Cu resources documented in this study is associated with deposit discovery, the incorporation of more resources within the database (i.e., better data coverage), and the growth of individual Cu resources (often coincident with production) by an average of ~13% between 2010 and 2015. Our data indicates that Cu resources continue to grow over time coincident with production, indicating that although discovery and (more importantly brownfields expansion) is clearly important in terms of meeting increasing demands for Cu, we need to move beyond merely considering grades and tonnages. Environmental, political, logistical, and economical factors (among many others) are likely to become increasingly influential controls on the conversion of resources to reserves and the future supply of Cu; in other words, reported Cu resources or reserves are not guaranteed to become copper production, with the reasons why this does or does not occur a key topic for future research.