mineral is found or processed, such as endangered species, water and air quality, and scenic beauty. Social availability accounts for the community acceptance of resource development and may be more commonly referred to as “social license to operate.” Political availability applies at local, national, and international levels and is a function of the predictability of laws, the independence of the judiciary, the limits on litigation, the protection of land tenure, the willingness of the host country to allow or facilitate development of the resource and repatriation of profits, and the military and economic stability of a region and the availability of an appropriate workforce. Economic availability considers the cost to discover the mineral deposit; to extract the minerals; and to process, concentrate, and purify the minerals balanced against the market value of the product. The availability of technical and skilled workforces is also a factor in economic availability. This chapter discusses the dimensions of primary and secondary availability and additional indicators of risk to the supply to clarify the input used to evaluate the risk to the availability of a mineral as a determinant of that mineral’s position in the criticality matrix.

Mineral deposits often have specific associations with geologic terrains and vary in abundance as a function of geologic time; a few examples of minerals and their global geologic associations are listed here. The major source of copper from deposits, known as porphyry copper deposits, are most prevalent around the Pacific Ocean, along the west coasts of South and North America and in the South Pacific islands of Indonesia, and in Papua New Guinea (Figure 3.1). The deposits in the United States formed 50 million to 75 million years ago, while the deposits in the South Pacific can be as young as 1 million to 3 million years old. Porphyry copper deposits are low grade (0.3-1.0 percent copper) and large tonnage (often greater than 1 billion tons), with the copper-bearing minerals finely disseminated throughout the large volume of rock. Platinum group metal