In the mid-1970s I taught an energy course at VPI&SU. I became interested in how minerals depletion was estimated and decided that I could do it better than had been done.
I used the least-squares-fit program of my colleague, Dr. Richard A. Arndt, to fit production-rate data for most minerals mined in the United States and the world.
Three books were published of that work:
Recently I have redone some of that work using the Solver part of Microsoft Excel to do the fits.
See Depletion Theory for a summary of the mathematics used in this research.
Verhulst Function for modeling minerals depletion.
Most recent minerals-depletion work: