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MINERAL RESOURCES, 1912.
within allowable limits of error due to the complex nature of the ores and of the methods of treatment. The figures of the mines report may be expected, on the whole, to fall normally below those of the mint report for the reasons outlined.
For the last eight years the final figures for mint and mine returns have been as follows:
Production of gold and silver, 1905-1912, according to mint and to mine returns.
These figures show an excess of gold, according to mint reports, for the eight years of $4,761,067, or a difference of a little over 0.6 per cent, but a deficit of silver production of 1,477,078 fine ounces, or a difference of a little more than 0.3 per cent. As figures for Alaska placers are not claimed to be as close as these, the differences for the United States proper are even lower. It is thought these relatively small differences may be accounted for by the explana­tions already given. For figures of any one year an excess of mining over smelting and refining, whether of gold and silver or of base metal ore, or both, is indicated by larger figures in the mine reports for gold or silver, or both; and normal relations, or perhaps excess of smelting and refining over mining by drawing upon stocks, is suggested by the reverse figures.
UNITS OF MEASUREMENTS.
Gold and silver are measured by the fine ounce. The computing tables to six decimals used by the Bureau of the Mint and the United States Geological Survey are based on the exact valuation for gold of $20.671834625323 per fine ounce. The average commercial price in New York for silver per fine ounce in 1911 was taken at 53 cents and in 1912 at 61.5 cents. The standard Survey unit for ore production is the short ton of 2,000 pounds.
PRODUCTION OP GOLD AND SILVER REPORTED FROM THE MINES.
The following table gives the quantity and value of gold and silver, by States, reported from the producing mines in 1912 to the United States Geological Survey. The increase or decrease of production shown results from comparison with the corresponding Survey mine figures for 1911.