The number of mineral deposits, large and small, discovered in North America over the last half millennium has not been tallied, but it must be in the hundreds of thousands. Most discoveries are small and of no more than local importance, but some are giants. As a result, Canada, Mexico, the Caribbean region, and the United States have at one time or another each been the world′s leading producer of one or more mineral resources. The complex diversity and the remarkable plenty of the deposits played a vital role in the development of North America′s vibrant societies. From the time of the first European settlers to the present, our use of, and dependence on, mineral resources has grown steadily larger.
Mineral consumption in North America has now reached enormous proportions. For the region as a whole, the mass of mineral resources used directly or indirectly in 1988, by every man, woman, and child, weighed 14 metric tons. There are ap-proximately 360 million people in the region. In Canada and the United States, annual per capita consumption is approximately 16 metric tons; in Mexico and the Caribbean, per capita consumption is lower—closer to 10 metric tons—but still considerable. Nonmetallic resources, such as crushed stone, sand, gravel, clay, cement, and plaster, account for a significant fraction of the consumed mass. Such materials tend to be locally produced, and the sources are so large and widespread that there does not seem to be any reason to suspect that supply limitations lie ahead. But even though supply problems may not be cause for concern, continued massive use of mineral resources does raise environmental concerns. The magnitude of mineral products mined each year now exceeds the magnitude of the sediment transported annually to the sea by streams. Inevitably, use of mineral resources is changing the global environment.