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 Teller being the leading producers. The Cripple Creek field in the last-named county is one of the most wonderful mining districts, past or present, of America. Leadville, in Lake county, is another. The district about Silverton (product 1870–1900 about $35,000,000, principally silver and lead, and mostly after 1881) has also had a remarkable development; and Creede, in the years of its brief prosperity, was a phenomenal silver-field. From 1858 up to and including 1904 the state produced, according to the State Bureau of Mines (whose statistics have since about 1890 been brought into practical agreement with those of the national government) a value of no less than $889,203,323 in gold, silver, lead, copper and zinc at market prices. (If the value of silver be taken at coinage value this total becomes vastly greater.) The yield of gold was $353,913,695-$229,236,997 from 1895 to 1904; of silver, $386,455,463-$115,698,366 from 1889 to 1893; of lead, $120,742,674—its importance beginning in 1879; of copper, $17,879,446-$8,441,783 from 1898 to 1904; and of zinc, $10,212,045—all this from 1902 to 1904. Silver-mining ceased to be highly remunerative beginning with the closing of the India mints and repeal of the Sherman Law in 1893; since 1900 the yield has shown an extraordinary decrease—in 1905 it was $6,945,581, and in 1907 $7,411,652—and it is said that as a result of the great fall in the market value of the metal the mines can now be operated only under the most favourable conditions and by exercise of extreme economy. In Lake county, for example, very much of the argentiferous ore that is too low for remunerative extraction (limit 1903 about $12.00 per ton) is used for fluxes. The copper output was of slight importance until 1889—$1,457,749 in 1905, and $1,544,918 in 1907; and that of zinc was nil until 1902, when discoveries made it possible to rework for this metal enormous dumps of waste material about the mines, and in 1906 the zinc output was valued at $5,304,884. Lead products declined with silver, but a large output of low ores has continued at Leadville, and in 1905 the product was valued at $5,111,570, and in 1906 at $5,933,829. Up to 1895 the gold output was below ten million dollars yearly; from 1898 to 1904 it ran from 21.6 to 28.7 millions. In 1897 the product first exceeded that of California. In 1907 the value was $20,826,194. Silver values ran, in the years 1880–1902, from 11.3 to 23.1 million dollars; and the quantities in the same years from 11.6 to 26.3 million ounces. In 1907 it was 11,229,776 oz., valued at $7,411,652. Regarding again the total combined product of the above five metals, its growth is shown by these figures for its value in the successive periods indicated: 1858–1879, $77,380,140; 1879–1888, $220,815,709; 1889–1898, $322,878,362; 1899–1904, $268,229,112. From 1900 to 1903 Colorado produced almost exactly a third of the total gold and silver (market value) product of the entire country.

In addition, iron ores (almost all brown hematite) occur abundantly, and all material for making steel of excellent quality. But very little iron is mined, in 1907 only 11,714 long tons, valued at $21,085. Of much more importance are the manganiferous and the silver manganiferous ores, which are much the richest of the country. Their product trebled from 1889 to 1903; and in 1907 the output of manganiferous ores amounted to 99,711 tons, valued at $251,207. A small amount is used for spiegeleisen, and the rest as a flux.

The stratified rocks of the Great Plains, the Parks, and the Plateaus contain enormous quantities of coal. The coal-bearing rocks are confined to the Upper Cretaceous, and almost wholly to the Laramie formation. The main areas are on the two flanks of the Rockies, with two smaller fields in the Parks. The east group includes the fields of Canyon City (whose product is the ideal domestic coal of the western states), Raton and the South Platte; the Park group includes the Cones field and the Middle Park; the west group includes the Yampa, La Plata and Grand River fields—the last prospectively (not yet actually) the most valuable of all as to area and quality. About three-fifths of all the coal produced in the state comes from Las Animas and Huerfano counties. In 1901 about a third and in 1907 nearly two-fifths of the state’s output came from Las Animas county. The Colorado fields are superior to those of all the other Rocky Mountain states in area, and in quality of product. In 1907 Colorado ranked seventh among the coal-producing states of the Union, yielding 10,790,236 short tons (2.2% of the total for the United States). The total includes every variety from typical lignite to typical anthracite. The aggregate area of beds is estimated by the United States Geological Survey at 18,100 sq. m. (seventh in rank of the states of the Union); and the accessible coal, on other authority, at 33,897,800,000 tons. The industry began in 1864, in which year 500 tons were produced. The product first exceeded one million tons in 1882, two in 1888, three in 1890, four in 1893, five in 1900. From 1897 to 1902 the yield almost doubled, averaging 5,267,783 tons (lignite, semi-bituminous, bituminous, and a steady average production of 60,038 tons of anthracite). About one-fifth of the total product is made into coke, the output of which increased from 245,746 tons in 1890 to 1,421,579 tons (including a slight amount from Utah) in 1907; in 1907 the coke manufactured in Colorado (and Utah) was valued at $4,747,436. Colorado holds the same supremacy for coal and coke west of the Mississippi that Pennsylvania holds for the country as a whole. The true bituminous coal produced, which in 1897 was only equal to that of the lignitic and semi-bituminous varieties (1.75 million tons), had come by 1902 to constitute three-fourths (5.46 million tons) of the entire coal output. Much of the bituminous coal, especially that of the Canyon City field, is so hard and clean as to be little less desirable than anthracite; it is the favoured coal for domestic uses in all the surrounding states.

Petroleum occurs in Fremont and Boulder counties. There have been very few flowing wells. The product increased from 76,295 barrels in 1887 to above 800,000 in the early ’nineties; it fell thereafter, averaging about 493,269 barrels from 1899 to 1903; in 1905 the yield was 376,238 barrels; and in 1907, 331,851 barrels. In 1905 the state ranked eleventh, in 1907 twelfth, in production of petroleum. It is mostly refined at Florence, the centre of the older field. The Boulder district developed very rapidly after 1902; its product is a high-grade illuminant with paraffin base. Asphalt occurs in the high north rim of Middle Park (c. 10,000 ft.). Tungsten is found in wolframite in Boulder county. In 1903 about 37,000 men were employed in the mines of Colorado. Labour troubles have been notable in state history since 1890.

Mineral springs have already been mentioned. They are numerous and occur in various parts of the state. The most important are at Buena Vista, Ouray, Wagon Wheel Gap, Poncha or Poncho Springs (90°-185° F.), Canyon City, Manitou, Idaho Springs and Glenwood Springs (120°-140° F., highly mineralized). The last three places, all beautifully situated—the first at the base of Pike’s Peak, the second in the Clear Creek Canyon, and the third at the junction of the Roaring Fork with the Grand river—have an especially high repute. In 1904 it was competently estimated that the mineral yield and agricultural yield of the state were almost equal—somewhat above $47,000,000 each.

In 1900 only 4.6% of the population were engaged in manufactures. They are mainly dependent on the mining industry. There are many large smelters and reduction plants in the state, most of them at Denver, Leadville, Durango and Pueblo; at the latter place there are also blast-furnaces, a steel plant and rolling mills. Use is made of the most improved methods of treating the ore. The cyanide process, introduced about 1890, is now one of the most important factors in the utilization of low-grade and refractory gold and silver ores. The improved dioxide cyanide process was adopted about 1895. The iron and steel product—mainly at Pueblo—is of great importance, though relatively small as compared with that of some other states. Nevertheless, the very high rank in coal and iron