et by domestic
production. The balance was obtained by importation, chiefly from
Germany, from Portugal and Spain, and from England, both of concentrates
and of ferrotungsten.

To the considerable demand for high speed tool steels occasioned by
munitions manufacture, production in the United States responded
quickly. Supplies of tungsten came chiefly from California, Colorado,
Arizona, Nevada, and South Dakota. At the same time importation largely
increased, chiefly from the west coast of South America and the Orient.
Consumption reached a half of the world's total. Considerable amounts of
ferrotungsten were exported to the Allies.

The end of the war created a possible tungsten shortage in this country
into a tungsten surplus. In so far as actual domestic consumption is
concerned there has been a return to something like pre-war conditions,
as the only known new use to which tungsten may be put--the manufacture
of die steel--does not involve the use of any large amount of
ferrotungsten. The richer mines of the two chief tungsten-producing
districts in the United States have shown impoverishment and at present
no important new deposits are known. The grade of the producing deposits
is on an average low. The domestic production of tungsten ore will
doubtless decrease, owing to the importation of cheaper foreign ores,
unless a high tariff wall is erected. Importation from the Orient and
the west coast of South America should continue in reduced amounts,
depending upon the ability of domestic manufacturers to obtain and hold
foreign markets for ferrotungsten and high speed tool steel. In the
commercial control of tungsten ores the United States has at present a
strong position, second only to that of England.

GEOLOGIC FEATURES

Tungsten ores contain tungsten principally in the form of the minerals
scheelite (calcium tungstate), ferberite (iron tungstate), huebnerite
(manganese tungstate), and wolframite (iron-manganese tungstate). All
these minerals are relatively insoluble and have high specific gravity,
and as a consequence they are frequently accumulated in placers, along
with cassiterite and other stable, heavy minerals. A large part of the
world's tungsten production in the past has been won from such deposits.
Placers are still important producers in China, Siam, and Bolivia,
although in these countries vein deposits are also worked.

With the exhaustion of the more easily worked placer deposits,
increasing