Stages in the metal supply process are affected by each of the following physical (geologic) factors: (1) geographic distribution of concentrations of potential ore minerals, (2) depth of these concentrations, (3) mineralogy, (4) grain size of the minerals, and (5) grade and (6) tonnages of the concentrations. For mineral deposits of each type in each geologic and political environment, the lowest cost metal will tend to be produced first because: (1) the largest deposits tend to be found first, (2) the few largest deposits should reap the benefits of economies of scale and will tend to account for the lion’s share of total metal, (3) higher grade deposits that require substantially less energy per ton of metal than do lower grade deposits will be mined first, and (4) deposits that have the mineralogy and grain sizes that are relatively cheap to process will be produced first. Shallow deposits that are relatively cheap to find and mine and deposits near existing infrastructure will also be produced first. Because stages in the supply process are sequential, problems at any stage caused by the physical factors are reflected in subsequent stages and adversely affect production costs. In the long term, effects of such problems will be not physical shortages of metals but a rapid or persistent increase in real prices of metals.