ng roscoelite (a vanadium-bearing mica) in fissures and
brecciated zones and replacing the cementing materials of flat-lying
sandstones. Locally the sandstones contain as much as 20 per cent of the
roscoelite. The deposits contain small amounts of fossil wood which may
have been an agent in the precipitation of the vanadium. There is
considerable doubt as to their origin, but it is generally supposed that
they represent concentrations by surface waters of minute quantities of
material originally scattered through the surrounding sediments; it has
also been suggested that certain igneous dikes in this region may have
had some connection with the mineralization. Deposits of carnotite, a
potassium-uranium vanadate, which have been worked for their content of
uranium and radium and from which vanadium has been obtained as a
by-product, are found as impregnations of the sandstone in these same
localities (p. 265).

There are other deposits containing small amounts of vanadium which are
not at present available as ores. Vanadinite, a lead-vanadate, and
descloizite, a vanadate of copper or lead, are found in the oxide zones
of a number of lead and copper deposits in the southwestern United
States and Mexico. Titaniferous iron ores, extensive deposits of which
are known in many places, usually contain a small percentage of
vanadium.

Outside of the Peruvian deposit, the affiliations of which are doubtful,
the vanadium deposits of economic importance owe their positions and
values mainly to the action of surface processes, rather than to igneous
activity.

ZIRCONIUM ORES

ECONOMIC FEATURES

The oxides of zirconium have high refractory properties which make them
useful for refractory bricks and shapes for furnace linings, for
chemical ware, and for other heat, acid, and alkali resisting articles.
For these purposes they find a limited market. Experimental work seems
to show possibilities of a very considerable use of zirconium as a steel
alloy; indeed, results are so suggestive that during the war the
government conducted an active campaign of investigation with a view to
using it in ordnance and armor steel. For such purposes the alloy
ferrozirconium is used, which carries 25 to 35 per cent zirconium metal.

The principal known deposits of zirconium ores, in order of commercial
importance, are in Brazil, in India, and in the United States (Pablo
Beach, Florida). The Brazilian and Indian deposits are also the
principa