The discovery of ore deposits, particularly those of world-class stature, is a rare and noteworthy event, not only for individual companies but for the minerals industry at large. Furthermore, the role of exploration leading to discovery in major companies has been greatly debated in recent times. The details of each discovery are unique, typically complex, and always of general interest, not only to fellow practitioners of the art and science of exploration but also to other members of the industry, including senior management. In particular, given that the majority of the mining industry’s wealth is captured in a few world-class, or Tier 1 mines, it is these rare deposits that provide the industry with the best opportunity to make a positive and lasting contribution to society.
The singular most important contribution geoscientists can make to society is the discovery of new deposits; it has been suggested that recently, junior companies are more successful and cost-efficient. However, over the decade spanning 1999 to 2010, Anglo American Exploration (AAE) discovered 15 base metals deposits and has been recognized as one of the most successful base metals explorers. AAE’s discovery odds and costs are in the lower quartile of the industry benchmark, whereas the resource tons and grade for the discovered deposits are in the top quartile.
In the past, the company’s priority has been competing with others in finding and building Tier 1 mines, but today the focus has changed to include building partnerships on all levels of society. Leadership, expertise, and a shared understanding of value creation are today the major differentiators for successful exploration and discovery. At Anglo American, effective management of the complex interplays of innovation and social licence, while at the same time encouraging a discovery-driven team culture, has resulted in delivery of growth options and distinguishes Anglo American from its peers.
Independent analysis of nine of the 15 AAE discoveries during the1999 to 2010 period indicates they were largely the result of tried-and-tested, although innovative field-based, activities carried out at carefully selected greenfield and brownfield sites, using novel, in-house technology where appropriate. For example, development of the low-temperature superconducting quantum interference device (LT-SQUID) allowed precise electromagnetic definition of massive sulfide bodies at three deposit sites.
All AAE discoveries were made by small, exploration-focused teams that were both highly motivated and suitably experienced. Importantly, some of the teams contained talented geoscientists who do not fit the usual corporate mold. For AAE, sustainable exploration today and success in the future therefore means delivery on advancing new exploration frontiers, maintaining access to land, quantifying mineral resources, and developing talent to provide options for growth through discovery, acquisition, and innovation.
Figures & Tables
Earth’s near-surface mineralogy has diversified over more than 4.5 b.y. from no more than a dozen preplanetary refractory mineral species (what have been referred to as “ur-minerals” by Hazen et al., 2008) to ~5,000 species (based on the list of minerals approved by the International Mineralogical Association; http://rruff.info/ima). This dramatic diversification is a consequence of three principal physical, chemical, and biological processes: (1) element selection and concentration (primarily through planetary differentiation and fluidrock interactions); (2) an expanded range of mineral-forming environments (including temperature, pressure, redox, and activities of volatile species); and (3) the influence of the biosphere. Earth’s history can be divided into three eras and ten stages of “mineral evolution” (Table 1; Hazen et al., 2008), each of which has seen significant changes in the planet’s near-surface mineralogy, including increases in the number of mineral species; shifts in the distribution of those species; systematic changes in major, minor, and trace element and isotopic compositions of minerals; and the appearance of new mineral grain sizes, textures, and/or morphologies. Initial treatments of mineral evolution, first in Russia (e.g., Zhabin, 1979; Yushkin, 1982) and subsequently in greater detail by our group (Hazen et al., 2008, 2009, 2011, 2013a, b; Hazen and Ferry, 2010; Hazen, 2013), focused on key events in Earth history. The 10 stages we suggested are Earth’s accretion and differentiation (stages 1, 2, and 3), petrologic innovations (e.g., the stage 4 initiation of granite magmatism), modes of tectonism (stage 5 and the commencement of plate tectonics), biological transitions (origins of life, oxygenic photosynthesis, and the terrestrial biosphere in stages 6, 7, and 10, respectively), and associated environmental changes in oceans and atmosphere (stage 8 “intermediate ocean” and stage 9 “snowball/hothouse Earth” episodes). These 10 stages of mineral evolution provide a useful conceptual framework for considering Earth’s changing mineralogy through time, and episodes of metallization are often associated with specific stages of mineral evolution (Table 1). For example, the formation of complex pegmatites with Be, Li, Cs, and Sn mineralization could not have occurred prior to stage 4 granitization. Similarly, the appearance of large-scale volcanogenic sulfide deposits may postdate the initiation of modern-style subduction (stage 5). The origins and evolution of life also played central roles; for example, redox-mediated ore deposits of elements such as U, Mo, and Cu occurred only after the Great Oxidation Event (stage 7), and major Hg deposition is associated with the rise of the terrestrial biosphere (stage 10; Hazen et al., 2012).