Table 3. Growth of extraction rates of geochemically scarce metals
Metal k, % per year td, years
Copper (1910-2002) 3.3 21
Zinc (1910-2002) 3.2 22
Nickel (1979-2002) 3.8 18
Tin (1959-2002) 1.8 39
Platinum (1979-2002) 4.9 14
  • The calculations were performed for the indicated ranges of dates (for which data were available).