ABSTRACT
Modern technology could not exist without non-renewable resources, yet the availability of these resources has seldom been a matter of much concern. Indeed, product designers have never been taught to regard materials as anything but commodities to be employed as necessary or convenient. The mineral resources used for millennia have come from rich deposits located near the Earth's surface, and thus potentially mineable. The most important are hydrothermal and magma processes, both involving fluids that dissolve elements and eventually deposit them in crystallised form. Materials whose cumulative supply curves follow predictable supply– cost patterns are unlikely to suffer from significant scarcity for at least several decades, although cost increases may over time change the spectrum of uses. For materials whose cumulative supply curves contain discontinuities or costs that rise rapidly with small increases in supply, however, virgin material scarcity, at least on a short-term basis, is a real possibility.
