Asbestos was first discovered in Arizona at two points in the Grand Canyon of the Colorado, west of the mouth of the Little Colorado River. The mineral occurs in a single bed, 12 to 14 inches thick, the veins being parallel with the bedding. In some places the veins are 4 inches thick, but usually they do not exceed 2¹⁄₂ inches. The visible supply, therefore, is not great, and as the district is difficult of access production has been slight. Asbestos also occurs in Ash Creek Canyon near Globe. Production began in 1914, and has increased considerably since. The asbestos carries only 0.5 per cent. iron oxide, while Canadian asbestos runs 2.2 per cent. to 2.6 per cent. iron oxide. The Arizona material is, therefore, superior to Canadian asbestos for electrical insulation. It is estimated that under favorable conditions the region can supply 1,000 tons annually for many years to come, but that the output will never be large as compared with that of Canada. In 1914 an asbestos deposit similar to those of Ash Creek was reported near Young postoffice. It is 80 miles from the nearest railroad station and will probably be inaccessible for many years. Near the summit of Mount Baker, north of the Roosevelt Reservoir, a mine producing good chrysotile was opened in 1917. The asbestos occurs in cross-fiber veins in limestone.
The asbestos deposits of Vermont are situated at Lowell, in the same formation as the Quebec deposits. The asbestos occurs in numerous irregular veins, the supply is probably large, and some of it compares favorably with the Canadian product. There was a considerable production in former years, but after 1912 the quarries were idle. The reserves of low-grade rock are probably large.
The main deposits of Wyoming occur south of Casper in igneous Archean rocks. The mineral is chrysotile asbestos, mostly of the cross-fiber type, though some slip-fiber is present. It is claimed that the Wyoming asbestos has better heat-resisting qualities than the Canadian fiber. However, a very small proportion of the fiber is of spinning grade.
Deposits of chrysotile asbestos have been noted in many parts of California, scattered over 13 counties. The deposits seem to be small, and thus far the production has not exceeded a few tons a year. A small production is recorded for 1917 from Nevada and Inyo counties. There was an increased output in 1918, the total being 229 tons. Some No. 1 spinning fiber was obtained in Nevada County.
Anthophyllite Asbestos.
—The anthophyllite asbestos deposits in Georgia yield the largest production of any state in the Union. The material is not of spinning grade and is practically all used for fireproofing and insulating. There is a considerable demand for such material, however, and the industry is established on a firm basis. A notable feature of the Georgia deposits is that approximately 95 per cent. of the rock quarried is fibrous anthophyllite of commercial quality, whereas in Quebec only about 6¹⁄₂ per cent. of the material quarried can be utilized.
Anthophyllite asbestos deposits occur in Virginia near Bedford. The material is low-grade and the amount is probably small. A little is consumed in the manufacture of “tenax,” a preparation used by dentists. Amphibole slip-fiber asbestos has lately been mined on a small scale in Maryland, near Pylesville. It is used for filters. Several years ago a small production was recorded from Dalton, Massachusetts, and New Hartford, Connecticut.
Anthophyllite asbestos occurs in Idaho, near Kamiah. It is not of spinning grade, is of low tensile strength, and is inferior to all but the lowest grades of chrysotile. The deposit is evidently large, but the production is almost negligible.
Canada and Newfoundland.
—The most important asbestos-producing deposits of the world are those of the province of Quebec, Canada, chiefly in the region of Thetford and Broughton. Asbestos occurs in serpentine of Cambrian age, the area in which the important mines are found extending from southern Vermont to Gaspé, in the Province of Quebec. The serpentine lies in three prominent belts. The Danville-Eastman-Vermont serpentine belt is about 62 miles long. The scattered outcrops probably are connected beneath the heavy drift deposits and forest growth. Prospects have been worked in six places, but the production attained is small. The belt is an uncertain quantity, that gives fair promise of a large future supply.