Ch. 1: Gold and Silver in 1908

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	GOLD AND SILVER.	175

	1907. The operators are chiefly doing development work. The three small stamp mills in the district were idle. In Surigao Province, in northeastern Mindanao, there has been considerable mining in a small way of auriferous quartz stringers in andesite, and in gravel and decomposed rock in place near the contact of andesite and chlorite schist. The gravel is worked both by ground sluicing and by panning, and as some of it yields over 8*1.30 in gold per cubic yard natives have made a fair living by working it. This district has had a small but steady output of gold, particularly from placer mines, for many years; but figures of production were not available until 1908. NUMBER OF MINES, ORE PRODUCTION, AND AVERAGE VALUES. The following table indicates the number of producing mines in 1908, divided into placer mines and deep mines. In the former mines values, generally in gold, are extracted from gravels or sands; the "deep mines" work deposits in solid rock which have not been disintegrated and sorted by erosion. The total number of mines is of course much larger than the figures given, because many properties for various reasons are idle or are being developed without having yet attained a producing stage. It is perhaps a little difficult, especially in the case of placers, to define what constitutes a mine. In some places a fairly large aggregate output is obtained, usually through traders and storekeepers, from transient or intermittent work of wandering miners which can not be credited to separate properties.



	The table shows the number of gold and silver producing mines in the United States. In the States of the Rocky Mountain region and the Pacific slope practically every mine producing lead, copper, or zinc also yields the precious metals. The table, therefore, actually records the number of producers of gold, silver, copper, lead, and zinc in these Cordilleran States. It also records the gold and silver producing mines in Michigan and in the Eastern States. It has not been possible to trace the production of Illinois to individual mines. Compared with the corresponding table for 1907 notable additions are found. The placer mines operated in 1908 are 2,599 in number,

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