The total gold production of the world'from the discovery of America by Columbus to' the year 1916 is estimated to be $16,616,991,763, Pure gold of this value would weigh about 20;500 tons, and occupy a space equal to 33,400 cubic feet. Graphically this amount could be represented by a solid circular tower of gold 20 feet in diameter and 138 feet high. The total yearly world production of gold since 1908 would have' increased the height of such tower about three and one-half feet each year. ,' The world's stock of gold is variously esti.. mated ; it cannot be positively known, as much of it is in jewelry, tableware, etc., in the hands of in dividuals. Some idea of the old gold industry may be gleaned, however, from the fact that the "sweep smelters° of the United States, who handle sweepings of the precious metals from refineries, and old goldand jewelry, did a busi ness of $22,000,000 in 1909. The gold leaf and foil industry is also credited with using about $1,000,000 of gold annually. The latest estimate of the world's gold, $9,000,000,000, is therefore probably below the real total. The United States, before the European War, was credited with nearly 52,000PM/100; Great' Britait) dyer $1400,000,000; France, about $1,200,0000001 Russia, $1,000,000,000, and Germany, $1,000,000;4 000. Many have thought. the German. total) an underestimate. Conditions' have tended to in crease the United States stock of gold, as this country's exports,have vastly exceeded the imp ports, and America is now far in the lead as a money centre.
United States.—The total yield of.. the ( mines of the United States from the first office cial records of 1792 to the close of the year 1916 has been 185,226,085 fine ounces, valued at $3,). 828,957,200. The 1916 output r of 4,479,056 ounces, valued at $92,950,300, •was won 'from seven various sources, as follows: 63.30 per cent ($57,799,310) from dry or -sificeotis ores! 25.06 per cent ($22,881,663) from placers; 9.07 per cent($8,286,290) from copper ores;. 1J63 per cent ($1,486,754) from lead ores; 0.65 per cent ($589,950) from lead-zinc ores; 0.19 per cent ($171,624) from tine ores, and 0.10 per tent ($92,039) from copper-lead and 'copper: lead-zinc ores.
In 1916 there were in .active operation ill the country 5,268. mines producing 'gold,. 3.20i of -these being deep or' lode mines,lnd. 2,068 placer.. mates. These figures include , silver mines whick.also as a by-product.
The largest 'number of mines in any one State is 852 in Colorado; 82S of these ate deep mines and 27 placers. In Nevada there•were 714 deep mines.and 65 placer mines; a total of 779. In Alaska there were.697 mines; 650 being placers and 47 deep mines. California has 589 mines; 297 of them. deep mines and 292 placer mines. Arizona has 527 mines; 504 deep mines and 23 placers. Montana has 393 deep mines and 120 placers; a total of 513. The 1916 output was produced chiefly (nearly 99 . per cent) by 10 States, with Alaska and the Philippines. See table under GOLD MINING AND METALLURGY.
In California the gold production is in pa `\ from deep mines lielding.hard quartz ores, and in part from placers. The deep mines in 1916 yielded $12,835,084, of which 72 per cent came from the. ores of copper mines. The placers yielded $8,575,657, of which $7,769,227 was re. covered by some 60 dredges operating in many sections of the State, but chiefly in Sacra._} mento and Butte counties.
In ,Colorado more than 92, per cent of the") 1916 output came from deep mines; about 4 per cent from placers (worked by dredges), and the remainder from lead and copper ores.
worthirds, of the total yield came from the T Cripple Creek district, where the Roosevelt tunnel was advanced 2,311 feet during the year; making its entire length at the close of 1916 about 22,000 feet.
In Alaska, the output was nearly two-thirds from the placer diggings, less than one-fourth of the , •placer gold being gained by the dredges. A little over 1 per cent was recovered from the copper mines, and the remainder from deep mines — nearly all , from the group of 13 low grade ore mines in southeastern Alaska: .
Nevada's 1916 output was gained nearly from deep quartz mines, and about half from the Goldfield and Tonopah 'districts. .
South Dakota's output came almost wholly from low grade siliceous ores.
The balance of imports and exports of for the calendar year 1416 shows a gain by the United States of $530,197,307. The imports were chiefly of foreign bullion, $514,425,434; of foreign coin, $155,034,343; and gold in foreign ore and base bullion, $13,402,002. The exports were in largest items: United States coin, $106,903,1:: ; domestic-refined bullion, $27,671, 406; and foreign coin, $20,:-:5,877. It is notable that the excess of imports over exports is $73, 000,000 more than the entire world's produc tion, of gold for the year.