even a survey of the science of geology as a whole. Our purpose is
rather to indicate and illustrate, in some perspective, the general
nature of the application of geology to practical affairs.

In professional preparation for the practice of economic geology there
is no easy short-cut. Students sometimes think that a smattering of
geological principles, combined with a little business and economic
information, may be sufficient. Analysis of professional successes
should make it clear that economic geologists are most effective and in
most demand, not primarily because of business aptitude, though this
helps, but because of their proficiency in the science of geology
itself. In short, to enter successfully the field of economic geology
one should first become a scientist, if only in a limited field.

The traditional conception of the geologist as a musty and stooped
individual, with a bag, hammer, and magnifying glass, collecting
specimens to deposit in a dusty museum, will doubtless survive as a
caricature, but will hardly serve to identify the economic geologist in
his present-day work. In writing this book, it is hoped in some measure
to convey an impression of the breadth and variety in this field. Few
other sciences offer so wide a range of opportunity, from the purely
scientific to the practical and commercial, coupled with travel,
exploration, and even adventure.

ECONOMIC APPLICATIONS OF THE SEVERAL BRANCHES OF GEOLOGY AND OF OTHER
SCIENCES

There is no phase of geology which at some time or place does not have
its economic application. Many references to these applications are made
in other chapters. It is proposed here to indicate briefly some of the
phases of geologic science which are most necessary to the practice of
economic geology. The student in his preparation cannot afford to
eliminate any of them on the ground that they are merely "scientific" or
"academic" or "theoretical."

MINERALOGY AND PETROLOGY

Mineralogy, the study of minerals, and petrology, the study of rocks
(aggregations of minerals), are of course elementary requisites in
preparation. There must be familiarity with the principal minerals and
rocks, and especially with the methods and processes of their
identification, with their nature, and with their origin. This involves
a study of their crystallography, chemical composition, physical
qualities, and optical properties as studied with the microscope. In
recent years the micro