Rare Metals. These include chiefly the following: Tungsten, molybdenum, vanadium and uranium. They are found in Colorado, Arizona, Germany, England and Sweden. The ores of these metals are unusual minerals, and the metals themselves are used in making special high grades of steel. Their salts are used in dyeing.
Thorium, cerium, lanthanum and yttrium, found in North Carolina, Norway, Brazil and Ceylon, are also to be classified under this head. Monazite, samarskite, thorite and other rare minerals contain these elements. They are used in preparing the mantles for incandescent gas lights.
Silver, the more common precious metal, is produced in greatest amount in the Rocky Mountains and the Andes. The United States, Mexico, Australia, Bolivia, Chili, Peru and Germany contribute nearly the entire supply. Montana, Colorado, Nevada and Utah lead in silver production in the United States. The ores are usually smelted and refined to purify the metal.
Argentiferous galena (lead ore) is the commonest ore of silver. The amount of silver per ton varies greatly. Zinc and copper ores often carry silver. Many sulphides of silver (argentite, pyrargyrite, etc.) are found, as well as chlorides and bromides (cerargyrite and bromyrite). Chloride and nitrate of silver are used in photography.
Silver is manufactured into innumerable articles for household use and personal adornment. The cheapest articles are not solid (sterling) but are electrically plated with a very thin coating of silver. Silver coins form the bulk of the currency of the world, although in most countries gold is the standard.
Sodium is the most important alkaline metal, and has a wide use.
Salt (rock salt, sea salt, lake salt, halite or sodium chloride) is the commonest natural compound of sodium. Important for food and in chemical manufacture.
Rock salt is mined in Germany, Austria, Spain, England, Louisiana, Kansas, India and other parts of the world. Obtained by evaporating salt water from wells in England, Michigan, New York, Ohio and China, or by evaporating salt water in the West Indies, Great Salt Lake, etc.
Besides its use for meat packing, curing fish, domestic purposes, etc., it is employed in silver refining, and the preparation of hydrochloric acid, soda ash, carbonate of soda and other chemical products.
Soda niter (nitrate of sodium) is a very easily soluble mineral. It is found in quantity only in the deserts of northern Chili, and is exported in large amounts to Europe and America for fertilizer and the manufacture of nitric acid and other chemicals.