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Since metals and other structural materials are
the stuff of which material possessions are made, metals
scarcity, reflected in high costs of production, could
restrict economic growth, which depends upon the
acquisition of new quantities of metals for use in new
structures, machines, and implements and to replace
metals lost through wear or dispersion. Xn this sense,
problems involving metals resources are the same as they
ever have been; but in the light of possible metals
scarcity, they have taken on new significance. Metal
that once lay undisturbed in the ground of Minnesota
and Upper Michigan already has been put to use and now
is found in rails that cross the country, in supporting
frames of giant buildings, and as wire and other
implements that serve to transport electric power and
telephone communications. These metals may be kept in
use, but if new additions to the metals stock are
required for future growth, they must be sought elsewhere,
or deeper in the same mines where ores already have
become lean.