91
The technology of the early nineteenth century
sufficed for gaining access to ore deposits at
considerable depths. Drilling, blasting, selective
mining of ore, rock support, pumping, hoisting,
concentration of ore minerals, their smelting, and
the refining of crude metals were all practiced
very effectively, . .(20)
Still, the ways in which these old activities
were performed in 1900 were very different from what
they had been in i860.
The greatest changes taking place at or near
the turn of the century, however, and the ones probably
having the greatest effect on levels of output were,
first, the introduction of non-selective mining, a method
that relied upon sophisticated techniques of concentra
tion and allowed lower yielding ores to be mined and
treated; and, second, the movement of mining into open
pits at the surface.
Non-selective methods permitted mining of not
only the very richest veins of metallic ores, but of
lower yielding surrounding ones as well. Once brought
to the surface, lower yielding ores could be processed
to yield higher concentrations of refined ore and
savings resulting from the elimination of extreme care
and painstaking classification in the mines more than
offset the increased costs involved in the processing
of lower grade ores at the surface. This process was
20
C. E. Julihn, "Copper: An Example of Advancing
Technology and the Utilization of Low-Grade Ores," in
Mineral Ec onomic s, ed. by F. G. Tryon and E. C. Eckel
(New York: McGraw-Hill Book Company, 1932), p. 123.