The New International Encyclopædia/Bauxite

BAUXITE, bōks′īt (from Baux; see below). The most important ore of aluminum, a hydrate having the composition Al₂O₃3H₂O, though most occurrences contain also some silica, iron oxide, and titanium. The ore occurs in rounded grains, in pisolitic or claylike masses. The grains usually show a concentric structure and a variable color from white to yellow, brown, or red. It is named from its occurrence at Baux, in France, but it is also known from Styria and Carinthia, in Austria, and from Antrim, in Ireland. In the United States it occurs in a belt about 60 miles long, extending from northwestern Georgia into northeastern Alabama, and also in Arkansas, near Little Rock. The foreign deposits result from the chemical alteration of igneous rocks; the American deposits are thought to be hot-spring formations. Those of Alabama and Georgia are basin-shaped, and are limited vertically to points between 900 and 950 feet above sea-level. The composition of good-grade American ore is approximately as follows: Alumina, 57 to 62 per cent.; ferric oxide, under 1 per cent.; silica, 2.5 to 3 per cent.; titanic acid, 3 to 4 per cent.; water (combined), 20 to 30 per cent.; moisture, retained mechanically, 2 to 4 per cent. While bauxite serves chiefly as an ore of aluminum., it is also employed in the manufacture of alum, and for lining basic converters and Siemens-Martin furnaces in the manufacture of steel. Consult: Hayes, "Bauxite," Sixteenth Annual Report United States Geological Survey, Part 3 {Washington, 1895); Mineral Industry, Vol. II. (New York, 1893); Branner, “The Bauxite Deposits of Arkansas,” Journal of Geology, Vol. V. (Chicago, 1897). See, also, the articles on Alum and Aluminium.