Page:The American Cyclopædia (1879) Volume V.djvu/327

 COPPER MINES about 1,500 tons each. The separate product of Wales in 1866 was about 650 tons; of Ireland, 1,335 tons. The number of mines in the Uni- ted Kingdom in 1862 was 228 ; 1863, 222 ; 1864, 201 ; 1865, 203 ; 1866, 173. The average yield of the ore is 7 or 8 per cent. The following tables exhibit the British trade in copper from 1857 to 1871 : Import*. Export, (foreign and colonial products). ImporU. Export, (foreign and colonial product.). s" 1 1 fr 1 =2 1 If 1 t 1 ii 1 2 f lj I" 3 1

1 !! 1 < Ton?. Ton*. Tons. Tom. Ton*. Ton*. 1858 1859 1860 1861 1862 1863 1864 97,099 84,465 97,817 94,480 117,483 102,099 93,304 2,138,880 1,812,028 2,011,558 2,003,226 2,631,056 2,000,473 2,054,674 7,366 11,829 12,649 16,224} 18,044 12,698 25,388 734,779 1,218,781 1,221,302 1,448,899 1,228,543 1,140,861 2,814,444 2,317 2,403 8,682 8,923 8,679 6,289 9,023 234,149 251,701 855,706 356,705 786,912 574,380 854,168 1865 1866 1867 1868 1869 1870 1871 122,248 129,547 102,782 114,036 110,968 106,632 78,691 269,864 2,440,754 1,801,155 2,069,873 1,999,285 2,015,128 1,777,551 22,144 21,409 80,018 85,535 81,885 29,964 82,542 1,978,576 1,687,567 2,201,584 2,550,712 2,229,513 2.01,544 2,157,425 9,847 14,092 14,160 20.851 12,140 14,519 17,253 852,714 l,l:;'2*4 1,0-50,675 1.4 849,904 972,15s 1,181,828 The relative amounts of ore and regulus im- ported have been as follows: 1868, 83,334 tons of ore and 30,702 of regulus; 1869, 72,199 and 38,769 ; 1870, 62,104 and 44,528 ; 1871, 48,215 and 30,476. Nearly all the regulus and the greater part of the unwrought copper are brought from Chili, while the ore is furnished by various copper-producing countries. EXPORTS (DOMESTIC PRODUCE). YEARS. Unwrought copper, tons. Value. Mixed or yel- low metal, tons. Value. Other sort, of wrought copper, tons. Value. Bras., tons. Value. 1857 7146 852 055 6,827 712 643 10670 1415898 1093 143953 1858 .... 6,719 699,622 5,945 573,147 12,124 1,426,771 1,382 155511 1859 6349 691,627 6678 639.340 9,695 1,121,308 1,288 149 030 I860 6>80 749,879 6,651 625,983 12,485 1,411,854 1,883 211,692 1861 4,868 483,410 6,745 585,140 10.666 1,129,305 1,522 171,050 1862 5088i 497,915 9,722 812,158 18,103 1,374,669 1,960 204,784 1863 12,797 1,188,713 11,680 953.457 18,610 1,849,425 2,895 241,895 1864 566,147 9,293 801,761 21,588 2,277,682 2.134 234,013 1865 5,569 496,148 9,950 816,640 16,089 1,617,422 2,212 232,309 1866 5,968 538,034 9,565 771,936 12,891 1,262,578 2,065 225.14S 1867 9,680 779,849 18,092 971,208 14,973 1,286,327 2,309 215,772 1868 8,184 666,665 13,318 915,747 16,697 1,410,337 2,118 205,129 1869 12,116 969,766 11,680 785,340 18,772 1,575,425 2,724 255,058 1370 .. . 10,671 795,868 12,284 795,702 15,493 1,228,283 2,878 247,075 1871 18958 1,055,032 12,975 870,962 12,377 1,022,549 8.511 818,998 The exports are to every quarter of the globe, but perhaps India is the most important mar- ket. The most important copper mines in the United States are those on the south shore of Lake Superior, where the metal occurs in the bedded trappean rocks, with interstratified sandstones and conglomerates, which are de- veloped to a greater or less extent in various localities along both sides of the lake, and are everywhere copper-bearing. The copper is almost wholly in the native or metallic state, and occurs in veins cutting the strata, associated with quartz and various spars and crystalline miner- als ; and also disseminated in the beds of rock, in which the richest and most productive mines of all are now wrought. While in some of the veins masses of pure copper weighing many tons are met with, the copper in the beds is generally in smaller masses or grains. In this state it occurs in the layers of soft amygda- loidal trap, locally known as ash beds ; while in other cases the pure metal appears as the cementing material of conglomerates or brec- cias made up of the ruins of red feldspar por- phyry rocks belonging to an older formation. Remarkable examples of this latter mode of oc- currence are seen in the Boston and Albany mine and the Calumet and Hecla mine, the latter of which yielded in 1872 the enormous amount of 8,000 tons of fine copper, or about one tenth of the entire product of the globe. The working of these mines of Lake Superior commenced in 1845, and from that period up to 1858 the entire production of the whole region amounted to a little over 16,000 tons. The cop- per is extracted by crushing and washing the rock, and is then in a nearly pure state, requiring only to be melted down to ingot copper. There are evidences that mines were worked in this region ages since by a primitive people who had only stone tools for their work. A cop- per region of great importance occurs in ad- jacent parts of the states of Virginia, North Carolina, Tennessee, and Georgia, where sul- phuretted ores are found in crystalline schists. For several years previous to 1861 the numer- ous mines in these regions were wrought in an imperfect manner; but the civil war, to- gether with the great depression in the price of copper which followed up to 1871, has caused these mines to be for the most part aban- doned, with the exception of those of Duck- town, Tennessee, which yield large quantities of ores that are smelted on the spot. With the
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