Survey_, 1909, p. 193.

[36] Butler, B. S., Loughlin, G. F., Heikes, V. C., and others, The ore
deposits of Utah: _Prof. Paper 111, U.S. Geol. Survey_, 1920, p. 195.

CHAPTER XII

MISCELLANEOUS METALLIC MINERALS

ALUMINUM ORES

ECONOMIC FEATURES

Bauxite (hydrated aluminum oxide) is the principal ore of aluminum. Over
three-fourths of the world's bauxite production and 65 per cent of the
United States production is used for the manufacture of aluminum. On an
average six tons of bauxite are required to make one ton of metallic
aluminum. Other important uses of bauxite are in the manufacture of
artificial abrasives in the electric furnace, and in the preparation of
alum, aluminum sulphate, and other chemicals which are used for
water-purification, tanning, and dyeing. Relatively small but
increasingly important quantities are used in making bauxite brick or
high alumina refractories for furnace-linings.

Aluminum is used principally in castings and drawn and pressed ware, for
purposes in which lightness, malleability, and unalterability under
ordinary chemical reagents are desired. Thus it is used in parts of
airplane and automobile engines, in household utensils, and recently in
the framework of airplanes. Aluminum wire has been used as a substitute
for copper wire as an electrical conductor. Aluminum is used in
metallurgy to remove oxygen from iron and steel, and also in the
manufacture of alloys. Powdered aluminum is used for the production of
high temperatures in the Thermite process, and is a constituent of the
explosive, ammonal, and of aluminum paints.

Deposits of bauxite usually contain as impurities silica (in the form of
kaolin or hydrous aluminum silicate), iron oxide, and titanium minerals,
in varying proportions. Bauxites to be of commercial grade should carry
at least 50 per cent alumina, and for the making of aluminum should be
low in silica though the content of iron may be fairly high. For
aluminum chemicals materials low in iron and titanium are preferred; and
for refractories which must withstand high temperatures, low iron
content seems to be necessary. The abrasive trade in general uses
low-silica high-iron bauxites.

The only large producers of bauxite are the United States and France,
which supplied in normal times before the war over 95 per cent of the
world's total. Small amounts are produced in Ireland, Italy, India, and
British Guiana. During the war a great deal of low-gr