Ore produced and average extraction value of gold and silver per ton in 1921, by States.' Philippine Islands, Illinois, and Missouri not included; quantity of crude ore containing gold and silver not known. 2 Includes only copper ore yielding gold and silver. Lead ore and zinc ore yielded no gold or silver. 5. GOLD AND SILVER PRODUCED AT MILLS IN THE UNITED STATES AND PERCENTAGE OF GOLD AND SILVER RECOVERED BY DIFFERENT METHODS OF TREATMENT AND FROM PLACERS. Gold and silver produced at mills in the United States and percentage of gold and silver recovered by different methods of treatment and from placers, 1911–1921.1 [Computed and compiled for the commission by J. P. Dunlop, U. S. Geological Survey.] 1 Philippine Islands excluded. Part of ore in some States (mainly South Dakota and Colorado) amalgamated followed by cyanidation of slimes and sands. 2 Also, 4,208.53 fine ounces of gold and 13 ounces of silver recovered by chlorination. 5 Percentage of production reported by mines in United States. Recovered by chlorination 15,819.5 ounces of gold in California and 7,668.5 ounces in Colorado; and sil. ver recovered by chlorination, 2,510 ounces in California and 20 ounces in Colorado. 7 1,263,867 tons of crude ore tailings and concentrates first treated by amalgamation, then by cyanidation. 81,568,315 tons of tailings treated by cyanida'ion after being treated by amalgamation. Value of gold recovered by chlorination, $185,510; value of silver, $1,399. 10 Recovered by chlorination, 21,878.08 ounces of gold in California and 3,202.89 ounces in Colorado; and silver recovered by chlorination, 3,747 ounces in California and 2 ounces in Colorado. 11 Represents crude ore and tailings, some of which were treated by amalgamation followed by cyanidation "Represents crude ore and tailings, some of which were treated by amalgamation followed by cyanidation. 12 Value of gold recovered by chlorination, $518,468; value of silver, $1,901. Recovered by chlorination, 15,979.47 ounces of gold in California and 4,366.50 ounces in Colorado; and silver recovered by chlorination, 634 ounces in California and 2,150 ounces in Colorado. "Represents crude ore and tailings, some of which were treated by amalgamation followed by cyanida tion. 15 Value of gold recovered by chlorination, $420,589; value of silver, $1,832. 15 Recovered by chlorination, 9,100.74 ounces of gold and 283 ounces of silver in California. Value of gold recovered by chlorination was $188,129; that of silver, $233. 17 Part of ore amalgamated followed by cyanidation of new tailings. Total ore and new tailings cyanided, 1,809,417 tons. 18 Recovered by chlorination, 5,769.83 ounces of gold and 3,631 ounces of silver in California. Value of gold recovered by chlorination was $119,173, that of silver, $3,631. 19 Part of ore amalgamated followed by cyanidation of new tailings. 1,161,161 tons. 20 No gold and silver reported as recovered by chlorination in 1919. was $119,173, silver $3,631. 21 Part of ore amalgamated followed by cyanidation of new tailings. 954,421 tons. Total ore and new tailings cyanided, In 1918 value of gold so recovered Total ore and new tailings cyanided 22 Part of ore amalgamated followed by cyanidation of new tailings-total ore and tailings cyanided 473,162 tons. 23 Also 1,245,419 tons of tailings from ore amalgamated was treated. |