nected with
the industry thoroughly understand the basic facts; for they are liable
to be called upon for advice, not only on questions relating to domestic
supplies affected by possible future foreign policies, but on the
formulation of the policies themselves. Conservation, cheaper steel, and
future trade relations of the United States all require consideration,
before action is taken to protect this one of several similarly situated
mineral industries, in the effort to make the country self-supporting.
These questions are further dealt with in Chapters XVII and XVIII.

Manganese production was also developed during the war in the Gold Coast
of West Africa, in Costa Rica, in Panama, in Java, and elsewhere; but
with the possible exception of Java and Chile, none of these sources are
likely to be factors in the world situation. The war-developed manganese
production of Italy, France, Sweden, and United Kingdom is also unlikely
to continue on any important scale.

GEOLOGIC FEATURES

Like iron ores, manganese ores consist principally of the oxides of
manganese (pyrolusite, psilomelane, manganite, wad, and others), and
rarely the carbonate of manganese (rhodochrosite). They are similar in
their geologic occurrence to many of the iron ores and are often mixed
with iron ores as manganiferous iron ores and ferruginous manganese
ores.

The higher grade manganese ores are of two general types. Those of the
Caucasus district in Russia are sedimentary beds, oolitic in texture,
which were originally deposited as rather pure manganese oxides, and
which have undergone little secondary concentration. They are mined in
many places in much the same manner as coal. Those of India and Brazil
are chiefly surface concentrations of the manganese oxides, formed by
the weathering of underlying rocks which contain manganese carbonates
and silicates. The origin of the primary manganese minerals in the
Indian and in some of the Brazilian deposits is obscure. In others of
the Brazilian ores, the manganese was deposited in sedimentary layers
interbedded with siliceous "iron formations," and the whole series has
subsequently been altered and recrystallized.

The manganese ores of Philipsburg, Montana, the principal large
high-grade deposits mined in the United States, were derived by surface
weathering from manganese carbonates which form replacements in
limestone near the contact with a great batholith of granodiorite. The
primary manganes