518 KEPOBT— 1887. 



Ifc is fortunate for the future of Californian mining that much placer 

 gold is obtained by ' deep mining '■ — carrying levels at the bottom 

 of the gravel beds, which often lie under a great thickness of lava. 

 This process, however, is less productive of gold ; it can only be 

 profitably employed where the drift is deep and covered with volcanic 

 rock, and where the rich ground is always at the bottom. 



' The results of actual practice in Nevada county and elsewhere 

 demonstrate that hydraulic mining, compared with drifting, employs 

 twice the number of men and extracts four to six times the amount of 

 gold per lineal foot of channel. The yield of the North Bloomfield 

 Channel by drifting has been ^150 per lineal foot of channel, while 

 hydraulicking the entire deposit in this locality has given a yield of 

 ^760 dollars per foot' (Bowie, 'Hydraulic Mining,' p. 86). 



The injunction against hydraulic mining applies only to the central 

 counties of California, and in other parts it is carried on as usual. 

 In the north-western part of the State it has of late years been de- 

 veloped ; here the rivers flow direct to the sea through deep canons, and 

 hydraulicking does not harm the streams nor interfere with agriculture. 



Colorado has increased from ^2,700,000 in 1880 to ^4,200,000 in 

 1885 ; this increase is mainly due to quartz-mining. The yield of gold 

 in Montana has nearly doubled since 1880, the figures being in 1880 

 ^1,805,764, in 1885 ^,300,000. Here, again, the increase has been 

 mainly from quartz-mining, aided by an increased yield of silver con- 

 taining some gold. In 1880, 64^ per cent, of Montana gold was from 

 placers ; in 1884 only 37 per cent, on a largely increased yield. 



There was a great rush to the Montana placers in 1862, some of the 

 richest deposits in the world being then worked here ; since 1862 over 

 ^150,000,000 of placer gold has been produced in this State. 



Nevada, which once stood so high in gold produce in consequence of 

 the Comstock,! fell in yield of gold to ^4,888,247 in 1880, and to 

 ^2,000,000 in 1882. This was the lowest yield. It increased to 

 ^3,500,000 in 1884. The silver production of the State has continued 

 to decline ; very little placer gold is raised (only 1 per cent, in 1881), so 

 that the increase is due to gold-vein mining. 



Dakota is remarkably steady in its yield of gold, almost the whole of 

 it coming from quartz veins in the Black Hill district, the placer gold 

 being only 2 per cent, of the whole, and the silver produce practically nil. 



Dakota is perhaps typical of the future gold. mining industry in the 

 United States. Crushing and amalgamating processes are here carried 

 to great perfection, so that low-grade ores are worked, and a large per- 

 centage of the gold value obtained. The average yield of the lodes is 

 only ^4 per ton ; but ore of only ^2 per ton is worked at a profit, the 

 expenses of mining and milling being less than ^1 per ton. 



Orego7i declined in yield of gold from ^1,097,700 in 1880 to ^660,000 

 in 1883 and 1884; it increased to ^800,000 in 1885. The greater part 

 of this is from placer mines, vein-mining having been as yet but slightly 



' Mr. Del Mar estimates ^18,002,006 gold and ^'20,570,078 silver from the Com- 

 stock in 1876. The total yield from 1859 to 1880 was about ^140,000,000 gold and 

 ^175 000,000 silver. 



