The use of zirconium for alloying in steel is so new that, pending definite determination by disinterested competent authorities of the exact properties, if any, which zirconium imparts to steel, judgment as to its value for this purpose should be withheld.
Zirconium carbide has been patented for filaments for incandescent electric lamps and it has also been used as an abrasive. Tried as a pigment, zirconia has been found to have good covering power and should be considered where protection from acids, alkalies, or gases is particularly desired. The basic acetate has been used for weighting silk, and the pure oxide is used as a substitute for bismuth subnitrate in X-ray work.
GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION
Zirconium occurs in nature in commercial quantities as a mixed oxide and silicate known as baddeleyite, sometimes called brazilite, and as the silicate, zircon. Baddeleyite, as supplied to the trade, usually carries 80 to 85 per cent. ZrO2. The silicate, zircon, carries about 65 per cent. ZrO2. The oxide deposits, containing as they do a higher percentage of zirconium and the ore being more pure and easier to reduce, will in all probability become the principal source of zirconium.
The principal known deposits of zirconium ores are in Brazil, India and the United States, the countries being named in the relative order of their commercial importance.
The Natural Oxide.
—The natural oxide, baddeleyite, or brazilite, occurs only in Brazil in commercial quantities and is described in Mineral Foote-Notes by Meyer,[99] who writes as follows:
[99] Meyer, H. C., Mineral Foote-Notes, November, 1916, p. 29.
There are but few commercial deposits of the unusual ores which present more interesting geologic as well as economic features than do the deposits of natural zirconium oxide in Brazil. The Caldas region (visited in 1915 by the writer) in which these zirconia deposits occur, is situated partly in the State of Minas Geraes and partly in the State of Sao Paulo, approximately 130 miles north of the city of Sao Paulo. It is a mountainous plateau, the main elevation of which is about 3,600 feet. The surface is undulating, presenting differences in level of from 300 to 600 feet.
The whole area is bounded on all sides by ridges rising abruptly from 600 to 1,200 feet above the general level and forming a roughly elliptical enclosure with a major axis of approximately 20 miles in length and a minor axis of 15 miles. This peculiar arrangement of the higher ridges is very significant when coupled with the fact that the predominant rock of the plateau is a phonolite and the presence of highly mineralized thermal water of considerable medicinal value.[100] No thorough geological survey has been made of this area with a view to determining the origin of the zirconia. The character of the ore, however, and the formation, seems to point to pneumatolitic agencies. A careful study of the relationship of the large masses of coarsely crystalline nephelite-syenite in this area, with pronounced segregations of eudialyte, might throw some light upon this subject.