Download PDF Winter Bridge on Frontiers of Engineering December 15, 2023 Volume 53 Issue 4 This issue features articles by 2023 US Frontiers of Engineering symposium participants. The articles cover pressing global issues including resilience and security in the information ecosystem, engineered quantum systems, complex systems in the context of health care, and mining and mineral resource production. Mineral Resources The Material Basis of Civilizations Wednesday, December 13, 2023 Author: Isabel Fay Barton Earth’s mineral resources have driven the advancement of civilization for the last five thousand years—and we have become dependent on an ever-increasing volume and variety of them. Throughout history, the extent of humans’ and societies’ achievement has depended on what materials are available. The most consequential of these, such as metals and fuels, have been derived from mineral resources, and their spread through society has created massive but invisible dependence on continued mineral resource supplies. Present technology depends on a larger amount and wider range of minerals than ever before (figure 1). This article provides a brief techno-historical summary of how our dependence on mineral resources reached its current unprecedented level. The Earliest Mineral Dependence For most societies, mineral resource dependence began with the Bronze Age (ca. 3200 BC in the Middle East, later in other regions). Copper, gold, and other mineral resources had been in use before as status and religious symbols, but bronze was the first material whose properties conferred a significant practical advantage over stone, antler, or flint. Bronze, an alloy of copper with arsenic or tin, is tough, strong, and holds a good edge. Most importantly, it melts at a relatively low temperature and can be cast in large lots with standard sizes, enabling the world’s first mass production. These properties of bronze changed the military and geopolitical landscape. With mass-produced standard weapons and armor, identically armed soldiers could operate as units with collective and individual advantages over adversaries armed with stone. This invention of the organized army contributed to the rise of empires. Particularly around the ancient Middle East, empires such as the Akkadians and Babylonians dominated their regions by organizing the production, working, and application of bronze weapons and armor (Gabriel and Metz 1991). However, maintaining power became conditional on maintaining supplies of copper and tin. In parts of the ancient Middle East in the second millennium BC, trade in both metals was tightly controlled by the government as a way of controlling the arms supply (Mirsky 1982). An exception to the Bronze Age pattern was sub-Saharan Africa, where copper and iron were used intensively prior to bronze, and iron became the metal on which most societies depended (Killick 2016). The Intensification of Mineral Resource Dependence During most of the Bronze Age, bronze remained relatively scarce. Most of society continued using Stone Age materials for tools and farm implements until copper and tin mining and bronzemaking had reached a very large scale. But even then, metals remained too rare and expensive for most people to have more than a small amount. This only began to change with the discovery of iron smelting. Though ancient iron was inferior to well-made bronze in hardness, corrosion resistance, toughness, and castability, it was far cheaper since iron ore deposits are orders of magnitude more common than copper or tin. Unlike bronze, iron was so widely available that archaeometallurgists call it the “democratic metal.” The average amount of metal to go around was still small—an estimated 1.5 kg of iron per capita per year during the Roman-era peak in preindustrial production—but was still several times more than ever before (Sim and Ridge 2002). The spread of iron tools began to raise agricultural and industrial production. This in turn supported population growth but also required iron-using societies to maintain or expand iron ore supplies to maintain the population and standards of living. Many also used bronze alongside iron and made currency from one or more of gold, silver, or copper. As metal use began to pervade the economic, social, and industrial (as well as military) fabric of societies, mineral resource dependence ratcheted up again. The Extension of Mineral Dependence In general, Iron Age societies’ mineral dependence was intensive but not extensive. Their suite of necessary mineral resources consisted of iron, copper, tin, gold, silver, lead, zinc, mercury, and salt. Many societies throve without one or several of these. But, though few, these mineral resources were intensively used, and even short-term supply interruptions could devastate economies and industries. To cite two instances, the exhaustion of the Central Asian silver mines caused a major financial crisis in China, and the Persian takeover of western Asia’s gold mines nearly strangled the gold-based Byzantine economy (Blanchard 2003). Mineral dependence intensified over the first to early second millennia AD, but in most societies, it did not become much more extensive. The main exception was medieval Eurasia, where new minerals came into use (figure 1) and then became vital as the population increased and use of the new resources became more common and intensive. Of the numerous examples, perhaps the two most consequential were nitrates and coal. Nitrates formed the basis for roughly 75% of gunpowder, which originated in China and slowly spread west, reaching western Asia and Europe around the fourteenth century AD. There it found a ready welcome in a region that probably had the highest frequency of wars per unit area of any place on earth at the time. As the first material since the Bronze Age to confer a nearly insuperable military advantage on the possessor, gunpowder became popular, and the associated technology improved rapidly. By the late 1600s, no army from Europe to western Asia was competitive without a large, steady, and well-organized supply of nitrates. Associated advances in gunpowder technology would lay the foundation for Europe’s global empires later. Coal-burning also started to become common in Europe during the fourteenth century. The combination of high population density, cold winters, and centuries of charcoal burning had deforested the region, and wood and charcoal became rarer and more costly. As a cheaper substitute, the poor began to burn lumps of coal washed up on beaches or picked up on hillsides. This marked the first use of minerals as fuel. By 1700, British inventors began using the heat to boil water to steam and using the steam to push a piston. Coal, as the only fuel that combined high-energy density, ready availability, and a cheap price, kicked off the Industrial Revolution. This was, above all, a revolution in the amount of power at human disposal (Smil 2017). Coal made power abundant, portable, and cheap for the first time in history, enabling a rapid rise in per capita power use (figure 2). Steam-powered factories replaced the handicraft system of manufacture, boosting output and decoupling it from the number of workers. The per capita GDP of industrializing economies soared compared to those that remained on a traditional or agrarian basis (Malanima 2016). Industrial nations’ manufactures began to dominate the global economy, while their industrialized and gunpowder-based military machines dominated their territory. But maintaining that dominance became conditional on maintaining large supplies of coal, as well as the iron, nickel, chrome, and other ferroalloy elements used in making the machinery and, of course, nitrates. Mineral resource dependence skyrocketed, increasing further as electricity required unprecedented amounts of copper and battery metals. Mineral Resource Reliance Today and in the Future From these beginnings, society’s mineral resource dependence has continued to increase in intensity and extent. Technologies that modern people take for granted, such as computers and cell phones, are predicated on an invisible, but vast and increasing, supply of materials mined from the earth’s finite mineral resources. Moore’s Law offers an example in microcosm. Between the 1980s and the early 2000s, the number of chemical elements required to make an advanced computer chip went from twelve to more than sixty (USGS 2017). The properties of gallium, platinum-group metals, and other elements enabled transistors to be made ever smaller without loss of performance, so that more and more could be packed onto a chip. The observed exponential rise in computing power is, at its base, a consequence of a nearly exponential rise in the number of mineral resource-based materials used to make computers. Virtually all modern technology follows a similar pattern of obtaining higher performance by extending dependence on mineral resources (Graedel and Miatto 2022). It is rare for a society to lower its dependence on mineral resources. Depressions and dark ages are the most common reasons. Less drastic but smaller in scale are decreases in dependence on individual mineral resources. For example, after the late 1800s, cyanidation replaced mercury-based methods of extracting gold and silver from ore, mostly eliminating society’s need for mercury (Habashi 2016). Otherwise, dependence usually shifts rather than decreasing. Green energy, for instance, is effectively the replacement of a consumable, short-lived, unrecyclable type of mineral resource (fossil fuels) with a durable, long-lasting, and moderately recyclable variety (metals). While this improves sustainability, the shift does not actually reduce dependence on mineral resources (Hammond and Brady 2022). In the long run, whether technology and standards of living can continue to advance will depend on whether adequate supplies of mineral resources continue to be available. At current levels of consumption, this is questionable. Each year we mine and add to circulation about as much metal as is contained in one world-class copper deposit, for example, which the earth can take millions of years to regenerate. The only long-term sustainable solution is to balance society’s demands with the earth’s finite supplies. Conclusions Since the Bronze Age, exploitation of the earth’s mineral resources has provided metals, fuels, and industrial minerals to enhance human capability. The unique physical, chemical, and electromagnetic properties of these materials have formed the basis for advancing technology, spreading industrialization, growing populations, and improving standards of living for the last five thousand years. But as mineral resources have become essential, we have also become dependent on an ever-increasing volume and variety of them. In the future, as in the past, what humans will be able to accomplish—individually or as societies—will continue to be a function of what mineral-derived materials are available for them to use. References Blanchard I. 2003. Mining, Metallurgy and Minting in the Middle Ages, volume 3. Stuttgart, Germany: F. Steiner. Gabriel R, Metz K. 1991. From Sumer to Rome: The Military Capabilities of Ancient Armies. New York: Bloomsbury Academic. Graedel T, Miatto A. 2022. Alloy profusion, spice metals, and resource loss by design. Sustainability 14:7535. Habashi F. 2016. Gold—an historical introduction. In: Gold Ore Processing: Second edition. M. Adams, ed. Boston: Elsevier. Hammond D, Brady T. 2022. Critical minerals for green energy transition: A United States perspective. International Journal of Mining, Reclamation and Environment 36(9):624-641. Killick D. 2016. A global perspective on the pyrotechnologies of Sub-Saharan Africa. Azania: Archaeological Research in Africa 51(1):62-87. Malanima P. 2016. Energy consumption in England and Italy, 1560-1913. Two pathways toward energy transition. The Economic History Review 69(1):78-103. Mirsky A. 1982. Influence of geologic factors on ancient Mesopotamian civilization. Journal of Geological Education 30(5):294-299. Sim D, Ridge I. 2002. Iron for the Eagles: The Iron Industry in Roman Britain. Gloucestershire, UK: Stroud Tempus. Smil V. 2017. Energy and Civilization: A History. Cambridge, Mass.: MIT Press. USGS (United States Geological Survey). 2017. Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply. USGS Professional Paper 1802. About the Author:Isabel Fay Barton is assistant professor of mining and geological engineering, University of Arizona.