Agricultural and chemical minerals are the most important of the numerous industrial minerals, a term that includes almost any commercial Earth material that is not a metal or fuel (Harben and Bates, 1984). The spectrum of industrial minerals extends from stone used for driveways to fluorine for your teeth and includes all of the minerals used for fertilizers, glass, and most chemical products. In the following two chapters, we have divided the industrial minerals into those used in agricultural and chemical markets, which are discussed in this chapter, and those used in the construction and manufacturing markets, which are discussed in the next chapter. Although some minerals, such as gypsum, have uses related to both groups, almost all of them have dominant markets on which this grouping is based.
The value of world agricultural and chemical minerals, almost $200 billion, is dominated by nitrogen, lime, and the fertilizer minerals potash and phosphate (Figure 12.1). In order of declining value of world production, the other minerals include salt, sulfur, fluorite, sodium sulfate, iodine, and bromine. The production history since 1960 for these commodities can be divided between nitrogen, iodine, and bromine, which have grown very rapidly, and all the rest that have not (Figure 12.1d, e). Within the laggard group, phosphate, potash, sulfur, salt, and sodium carbonate have not even kept pace with our bellwether, steel. Prices of phosphate, potash, and iodine have greatly exceeded the CPI, but all of the others have fallen behind significantly (Figure 12.1b, c). Production and reserve data for these commodities are given in Table 12.1.
With the exception of nitrogen and fluorite, deposits of the major agricultural and chemical minerals are formed during the normal evolution of a marine sedimentary basin, that is, a basin filled with sediment and seawater or freshwater. The distribution of these mineral resources reflects the location of ancient oceans, particularly shallow areas that extended onto the continents (Reading, 1986). Some of the less important minerals in this group formed by evaporation of non-marine lakes.