Fig. 14.—Distribution of potash deposits in northern Germany.
In 1904 another important and extensive deposit of water-soluble potash salts was discovered by boring in the valley of the Rhine River in southern Alsace. Alsace, then in possession of Germany, has now been restored to France. The deposit is in two essentially continuous beds that underlie within accessible depth an area of 70 to 80 square miles of the flat bottom lands of the Rhine Valley. The beds are estimated to contain about 1,500,000,000 metric tons of crude potash salts, which average considerably richer in potash than the output of the north German deposits, and, being of simpler chemical composition, are more readily refined. The mines opening these deposits are readily accessible to water transportation by way of the Rhine River and the canals of the Rhine Valley. The distance to ocean ports is considerably longer than it is from the north German deposits, being about 375 miles, as compared with 150 miles by canal and river boats from the latter, but the amount of handling necessary to transport similar cargoes from the two districts seems to be about the same. The deposit in Alsace lies in an elliptical area centering about 5 miles northwest of the city of Mulhouse.
Some potash has been produced from a deposit in Galicia, near Kalusz, south of Lemberg, from deposits reported to be of a type similar to those of north Germany, but the field has never yielded even enough potash to satisfy the local demand, and is thought not to be large.
During the war relatively small outputs of potash salts were obtained from many independent sources, in the United States, Abyssinia, Tunis, and other countries. Under stress of war necessities and the complete shutting off of other supplies, these outputs in the aggregate formed a considerable amount. Much of the development probably will not be permanent, when strict competition with the potash from more available sources is renewed, but each of these fields and doubtless many others contain the possibilities of development that may give the world situation a new aspect at any time. Chief among the most immediate prospects for important development is a rather extensive field in eastern Spain, near Barcelona. This field has not as yet produced on a commercial scale. One estimate of the reserves in the Spanish field claims a proved area of 13.5 square miles containing 200,000,000 tons of potassium oxide.
The nitrate deposits of Chile contain a small percentage of potash, and this is being recovered separately from the sodium nitrate at several of the refineries. It has been estimated that a total production of 240,000 tons of potassium oxide annually might be derived from this source.
Many different sources in the United States are yielding potash salts. The largest known deposit of soluble potash in fairly concentrated form is at Searles Lake, California. This is a dried saline lake, now represented by a bed of crystalline salts with a large amount of saturated brine rich in potash. The body of salts carrying the brine underlies an area of about 25 square miles and extends to an average depth of 70 feet. It is estimated that the brine alone in this deposit carries nearly 20,000,000 tons of potassium oxide, which would be enough potash to supply the needs of the country for about 60 years at the present normal rate. Numerous small lakes in western Nebraska carry brines exceptionally rich in potash, and these are now yielding a considerable production of potash fertilizer salts. No satisfactory estimate of the reserves in this field is available.
Under present operating conditions about one-third of the annual requirements of the United States is recoverable from the cement mills. About 380,000 short tons of potash, most of which is volatilized, is annually charged into the blast furnaces of the country. The best available estimates indicate that about 30,000 tons of potash have formerly gone to waste in molasses distillery slop, and-about 8,000 tons in Steffens waste water at the beet-sugar refineries of the country. Kelp and alunite are available in quantities sufficient to continue to yield a substantial production. Enormous quantities of leucite lava, carrying 10 per cent. of potash in an insoluble silicate form; greensand carrying 6 to 7 per cent. of insoluble potash; sericite with from 7 to 12 per cent., and feldspar with similar content, are available as raw materials of production if satisfactory commercial processes can be developed. Thus potential supplies of potash in the United States are practically inexhaustible. The future of the American potash industry, therefore, depends on the development of processes or methods of separation economical enough to permit the domestic product to compete with imported potash.
GEOLOGICAL DISTRIBUTION
The potash deposits of northern Germany lie in the midst of a series of formations known as the Zechstein, the geologic age of which is Permian. Both the Alsatian and Spanish deposits are found in Oligocene Tertiary rocks, although the deposits were not necessarily strictly synchronous in origin. The Galician deposits are described as of lower Miocene (Tertiary) age. These are the principal known bedded deposits of potash in the world, for which as a class the distinction as to geologic age seems to have a special significance. The association of potash with the large salt and gypsum deposits of the world seems for some reason to have been exceptional in geologic history. But the determination that these somewhat analogous occurrences have been formed at various times and places is a good basis for expecting that similar deposits may yet be discovered elsewhere.