Ch. 1: Gold and Silver in 1906

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	134	MINERAL RESOURCES.

	now only about 15,000,000 ounces. Idaho is far in the lead, with over 7,500,000 ounces, chiefly from the low-grade lead ores of the Coeur d'Alene district, which only average about half a cent in gold and 5 ounces in silver per ton. These figures are of course materially raised by concentration of the ore. Colorado follows Idaho with a production of about 3,500,000 ounces, a notable loss compared with 1905 and with 1904. Aspen, Leadville, and Clear Creek continue to be the most productive districts. Utah ranks third, with about 2,700,000 ounces, which is notably less than the output of 1905. Park City district still further reduced its output of silver from lead ores. Arizona ranks fourth, with 700,000 ounces, to which Tombstone ores contribute largely. Montana, formerly an important producer of lead ores, now ranks fifth, with an output of onlv 500,000 ounces. Oxidized lead ores now yield very little silver. Ores of this character are about exhausted. Small quantities are still furnished by Leadville, Aspen, and other placers in Colorado, and by Arizona, New Mexico, and Nevada. Copper-lead ores.—Ores of this character, more or less mixed with sphalerite, are marketed almost exclusively from Utah, with a smaller quantity from Montana. The Tintic and Park City districts j'ielded nearly the whole of the Utah production, most of it coming from the former district. These ores are rich in silver, and 6,500,000 ounces represented their yield, an increase of about 1,000,000 ounces compared with 1905. Zinc ores and zinc-lead ores.—The zinc ores proper contribute a very small amount of silver. Zinc-lead ores are produced chiefly in Colorado, and in 1906 yielded about 2,300,000 ounces. They are usualty concentrated with zinc and lead products. The division between the two classes is more or less arbitrary, but the greater activity in zinc mining is clearly reflected in the total silver yield from these ores, which was about 2,370,000 ounces, against 1,720,000 ounces in 1905.

	PRODUCTION BY STATES AND TERRITORIES. ALASKA.^a By Alfred H. Brooks. INTRODUCTION. An increase of nearly 50 per cent in the value of the gold output of 1906 over that of 1905 is the most concrete evidence of the advance of gold mining in Alaska. That copper mining, too, has undergone a rapid expansion is manifest by an increase of at least 20 per cent in production over the previous years. This progress has consisted chiefly in the development of the older districts rather than in the discoveries of new mineral fields, and can therefore be interpreted as an index of continuous advance rather than of abnormal expansion. Though the placer mines of Nome and Fairbanks were " Much of the work of compiling this report was done by C W. Wright, who paid special attention to the lode deposits; bv Sidney Paige, who compiled the data on placers, and by A. G. Maddren, who compiled the placer statistics. ' Many of the statements are taken from Bull. U. S. Geol. Survey No. 314.

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