l sources of monazite (pp. 288-289). The United States controls
one of the important Brazilian deposits. Germany before the war
controlled the Indian deposits, and is reported to have taken much
interest in the development of zirconium steels. During the war German
influence in India was effectively broken up. The use of zirconium has
been in an experimental state, and known sources of supply have been
ample for all requirements.

GEOLOGIC FEATURES

The zirconium silicate, zircon, is a fairly common accessory constituent
of granitic rocks and pegmatite veins. From these rocks it is separated
by weathering, disintegration, and stream transportation, and, having a
high specific gravity, it becomes concentrated in placers. The deposits
of southern India, of the coast of Brazil, and of Pablo Beach, Florida,
all contain zircon along with ilmenite, garnet, rutile, monazite, and
other insoluble, heavy minerals, in the sands of the ocean beaches.
Smaller deposits of zircon-bearing sands exist in rivers and beaches in
other parts of the United States and in other countries, but none of
these deposits has thus far proved to be of commercial importance.

The largest and most important zirconium deposits are on a mountainous
plateau in eastern Brazil and are of a unique type, entirely different
from those just described. They contain the natural zirconium oxide,
baddeleyite or brazilite, mixed with the silicate, the ore as produced
carrying about 80 per cent zirconia (ZrO_{2}). The ores consist both of
alluvial pebbles and of extensive deposits in place. The latter are
associated with phonolite (igneous) rocks, and seem to owe their origin
to the agency of hot mineralizing solutions from the igneous rocks.

TITANIUM ORES

ECONOMIC FEATURES

Titanium is sometimes used in steel manufacture to take out occluded
gases and thus to increase the strength and wearing qualities. Its
effect is to cure certain evils in the hardening of the molten steel,
and it is not ordinarily added in amounts sufficient to form a definite
steel alloy. Aluminum is frequently used in place of titanium. Titanium
is added in the form of ferrotitanium, containing either about 15 per
cent titanium and 6 to 8 per cent carbon, or about 25 per cent titanium
and no carbon. Titanium compounds are also used in pigments, as
electrodes for arc-lights, and by the army and navy for making
smoke-clouds.

The United States has domestic supplies of titanium suff