ever, are rather financial than commercial; nevertheless the following table is added to show the results mentioned above: Value of imports for consumption and of exports of mineral products in the calendar years 1912 and 1913, including gold and silver. PREFATORY NOTE TO THE GENERAL AND MINES REPORTS ON GOLD, SILVER, COPPER, LEAD, AND ZINC. By H. D. MCCASKEY. In the mining industry five metals are closely related in both the genesis and the geologic occurrence of their ores; they also hold together in mining and in metallurgical treatment. They are gold, silver, copper, lead, and zinc. Of their ores, some contain all five metals, many contain three or four, and few contain only one. Gold and silver, for instance, on the one hand, and lead and zinc, on the other, almost always stand in close genetic relations, and the ores of each two are usually mined together. Copper ores almost invariably produce some silver and gold as well as copper, and lead ores, with certain exceptions, produce notable supplies of silver. Zinc ores in the Western States contribute also to the silver production. In the same mine sometimes, and in the same mining district frequently, all five metals occur in commercial quantity. This situation is recognized by the United States Geological Survey in its publication of the annual reports on the mineral resources of the country; hence the general treatment of each of the five metals in the general reports and the grouping together of the related metals in the various mines reports descriptive of individual or geographically grouped States. To facilitate advance publication the complete report upon these five metals is therefore divided into sixteen sections, each of which is published separately. The first four sections give figures of output for the calendar year in marketable form for the metals named as obtained from the smelters, refineries, and mints, and general reviews of the respective industries for the entire country; the last twelve sections give the production as obtained from the mines so far as possible in terms of recoverable metal in ores and other material sold or treated during the calendar year, and supply information in detail relative to the mining industry in the respective States, counties, and mining districts. The figures given in the general reports are the final official statistics of production for the country and of the States. The general report on gold and silver includes the statistics of recovered precious metals as determined jointly by the Bureau of the Mint and the United States Geological Survey. CLXXI The sixteen sections, which appear as separate chapters in this volume, are as follows: Gold and silver (general report). Copper (general report). Zinc (general report). Gold, silver, copper, lead, and zinc in the Eastern States (mines report). Gold, silver, and copper in Alaska (mines report). Gold, silver, copper, lead, and zinc in Arizona (mines report). Gold, silver, copper, lead, and zinc in California and Oregon (mines report). Gold, silver, copper, lead, and zinc in Colorado (mines report). Gold, silver, copper, lead, and zinc in Idaho and Washington (mines report). Gold, silver, copper, lead, and zinc in Nevada (mines report). Gold, silver, copper, lead, and zinc in New Mexico and Texas (mines report). In measurement of ores, concentrates, and similar material the short ton of 2,000 pounds is used throughout. The ore classification is necessarily arbitrary in part. An ore is generally understood to be worked at a profit for one or more metals. The complex nature of western ores, especially, and the gradations from one well-recognized class to another render essential some fixed measures for the terminology used. The dry or siliceous ores comprise gold and silver ores proper, as well as fluxing ores carrying considerable quantities of iron and manganese oxides and very small quantities of gold and silver, and also precious metal bearing ores carrying copper, lead, or zinc in quantities too low to classify them as copper, lead, zinc, or mixed ores. The copper ores include those carrying over 21 per cent of copper, or even less in the cases of the great disseminated copper deposits of the West and of the copper ores of the Lake Superior region. In general, the lead ores are those containing over 4 per cent of lead, and the zinc ores are those containing 25 per cent or more of zinc, both irrespective of their precious metal content; but some ores of lower grade in lead, and especially in zinc, are treated profitably for these metals, and of course they are then classified as lead or zinc ores, as the case may be. The mixed ores are combinations of the ones enumerated. The price per unit of metal production (gold excepted, which is fixed by law at $20.67+ per fine ounce) is based upon averages of daily market prices current at New York for silver, copper, and lead, and at St. Louis for metallic zinc or spelter. The prices used by the United States Geological Survey for calculation of values for the years 1850-1913, inclusive, are as follows: It is to be understood, of course, that full market values are not received by producers for metals in ore and intermediate products, nor always for metals in marketable form, that payment is made in accordance with contracts for treatment or sale, and that, therefore, average daily quotations do not necessarily agree with average prices received. Each of the 16 sections mentioned is published in a separate pamphlet for advance distribution, and copies can be obtained, as long as the supply lasts, on request made to the Director, United States Geological Survey, Washington, D. C. |