2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 115-6
Presentation Time: 10:15 AM


BRANHAM, Jesse P. and JOHNSON, Aaron W., Natural Sciences, Northwest Missouri State University, 800 University Drive, Maryville, MO 64468

Skinner (1976) analyzed the rate of metal resource use relative to the abundance of ore minerals and found that the crustal distribution of elements in the Earth’s crust sets natural limits to the availability of metals contained in crustal material. As the demand for metals increases, the supply of ore minerals decreases. Eventually a less easily processed mineral must be utilized as a metal source. Because crustal abundance limits the supply of suitable ore minerals, easily processed ores are more rapidly exhausted, leaving only mineral sources that are very expensive to mine and process. Skinner concluded that humanity would experience a second Iron Age, likely within the next 35 to 50 years. We reconstructed Skinner’s study in an effort to understand how metal usage has changed, to investigate the role of new resources, and to investigate the role of changes in technology. We compared annual iron production to crustal abundance of iron and used this ratio as a baseline of production compared to availability. We created 6 other lines, 3 at orders of magnitude greater (10. 100, and 1000 times the iron ratio) and 3 at orders of magnitudes lower (0.1, 0.01, and 0.001 times the iron ratio). We used annual production data from the World Bureau of Metal Statistics for 1977, 1989, 2001, and 2012 in an effort to identify temporal variation in rate of metal production. We analyzed metal production data for zinc, lead, copper, mercury, silver, gold, tin, nickel, molybdenum, titanium, magnesium, manganese, aluminum, and tungsten. We found that all metals except mercury, silver, magnesium, and manganese are being used at a greater rate relative to their crustal abundance than in 1977. Nickel and molybdenum are being used at a slower rate than iron. Interestingly, the rate of use of mercury dropped precipitously (from 1000X that of iron to less than 0.01 the rate), likely as a result of toxicity effects associated with mercury use. Silver exhibited essentially no change. Temporally, the greatest increases in production and use for most metals occur between 2001, and 2012. It appears that the global economic downturn had little effect on resource demand. This increase likely reflects increased demands for goods in emerging economies in Asia and Africa.