Critical Minerals
Travis Hudson, American Geosciences Institute, 4220 King Street, Alexandria, VA 22302

Minerals and useful materials derived from them – mineral commodities – are the physical and economic foundations of society (Do We Take Minerals for Granted?).  For example, the U. S. Geological Survey (USGS) compiles production and consumption data for 84 mineral commodities used in America (Mineral Commodity Summaries).  These include metals like iron and copper but also many less well known elements such as indium and scandium. Some of these mineral commodities are not only important to our everyday life (it takes 60 elements obtained from minerals to make the latest version of our cell phones and computers) but they also face potential supply restrictions.  These are called “critical mineral commodities” or just “critical minerals”.

The economic importance of critical minerals, increasing global competition for them by rapidly developing countries, and the potential for supply disruptions triggered a recent study by the National Research Council (NRC).  The final report of this study – Minerals, Critical Minerals, and the U. S. Economy – develops a method for characterizing a minerals “criticality”. The method evaluates a mineral’s importance and its availability at a specific scale (such as nationally) and time (such as the near term from one to several years).

A mineral commodity’s importance can be characterized by factors such as the dollar value of its U. S. consumption, the ease with which other minerals can be substituted for it, and the outlook for emerging uses that can increase its demand. A way to evaluate the significance of these factors is to consider the impact that a lack of availability would have on them. How would the mineral’s uses or price change if it were less available?

A mineral’s availability depends on several factors including how much has been discovered, how efficiently it can be produced, how environmentally and socially acceptable its production is, and how governments influence its production and trade.  Many of the technological, social, and political factors have become increasingly important influences on mineral availability. For example, China produces most of the world’s rare earth elements (the U. S. gets 92% of its rare earths from China; Figure 1). By curtailing export shipments of these technologically key elements in 2010, China drastically affected their global availability (China Consolidates Grip On Rare Earths).

The criticality evaluation method developed by the NRC study relates the importance and availability of a mineral in a “criticality matrix” (Figure 2).  The matrix uses evaluations of the impacts of supply restrictions (the importance of the mineral) to the potential for supply disruptions. The greater both of these measures are the more critical the mineral is. The criticality assessments included in Figure 2 are for selected mineral commodities and show that platinum-group and rare earth elements are much more critical mineral commodities than others such as copper, titanium, and lithium.

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Bar graph of mineral commodities, by percentage imported
(click image to enlarge)

Figure 1.  Mineral commodities for which the U. S. imports at least 81% of its annual consumption. For example, 100% of U. S. rare earth consumption is imported and 92% of this comes from China. (U.S. Department of the Interior and U.S. Geological Survey)

Graph of the criticality of 11 mineral commodities
(click image to enlarge)
Courtesy of the National Academies Press

Figure 2.  Criticality matrix for 11 mineral commodities evaluated in the NRC study, Minerals, Critical Minerals, and the U. S. Economy, 2008. (Reprinted with permission from the National Academy of Sciences, Courtesy of the National Academies Press, Washington, D.C. )

Additional Resources:
Rare Earth Elements In the United States

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