Januakt 6, 1911] 



SCIENCE 



grade is sufSciently high. The ores which 

 are directly smelted reach the minimum of 

 copper in the Boundary district of British 

 Columbia, but associated gold and silver 

 raise the value per ton above four dollars. 

 Copper ores yielding copper alone were 

 smelted at Ducktown, Tenn., during long 

 campaigns at a little less than 2.5 per cent. 

 In earlier years and in many mining dis- 

 tricts ores as high as 20 per cent, were 

 found, rarely even higher, but they in time 

 were exhausted and five per cent, would be 

 quite rich for day in and day out averages. 



These statements will serve to establish a 

 point of view and likewise afford a stand- 

 ard of comparison. What is the outlook 

 for the future of copper production? 



We can not predict copper with the cer- 

 tainty of iron. It seldom appears in bed- 

 ded deposits which can be measured. In 

 the deep mines we can not always see ahead 

 for more than a year or two. In some 

 mines we know from exceptionally com- 

 plete development, of twenty years' sup- 

 ply. But the great advance in copper 

 mining has been the entrance of relatively 

 low-grade ores into the productive field. 

 The wall rocks of ten years ago have be- 

 come the ores of to-day. Where we find 

 in porphyries or schists copper sulphide 

 disseminated in fine particles or as coat- 

 ings along crevices, and in sufScient rich- 

 ness to yield two to two and one half per 

 cent., throughout very large bodies, it can 

 be mined very cheaply and concentrated 

 in enormous quantities so as to return a 

 safe margin. If the ore lies near the sur- 

 face, steam shovels make excavation ex- 

 tremely low in cost. The huge pits and 

 open cuts of this type of mine in the west 

 are now among the great sights for the 

 traveler. Mills whose insatiable crushers 

 take as much as eight or ten thousand tons 

 per day are no longer unknown. The drill 

 blocks out the ore long before mining be- 



gins, and reserves can be estimated more 

 closely than in the vein mines. 



If a mine is called upon to furnish a mill 

 with 2,000 tons per day and we allow 300 

 working days in the year, 600,000 tons 

 must be supplied per annum. For a life 

 of twenty years, a time practically de- 

 manded of such an enterprise to justify 

 the great expense of installation, at least 

 12,000,000 tons must be shown by the drill 

 before the enterprise can safely begin. If 

 we expect to mine three times this amount 

 per day we call for three times as much 

 ore. These figures, large as they may seem, 

 are not beyond the estimates of ore bodies 

 as now blocked out in several places in the 

 west, and even with these great demands, 

 twenty years supply and even more in in- 

 stances have been demonstrated. 



Let us now imagine again a 2,000-ton 

 daily output of say 2.25 per cent, ore, of 

 which the mill saves two thirds, or 30 

 pounds of copper in the ton. The output 

 in copper per day will be 60,000 pounds,. 

 or 30 tons and for the year 9,000 tons. 

 Should three new companies start up with 

 four or five times this output, 36,000 to> 

 45,000 tons will be added to a yearly sup- 

 ply, which in 1909 was 552,668 tons. We 

 see great need of a growing demand in 

 order that these vast contributions may be 

 absorbed. Yet I have made no unreason- 

 able assumptions nor have I overstepped 

 the practical certainties of the next few 

 years. 



How long will our copper hold out? 

 Mines come and go, and for the immediate 

 future there will certainly be no scarcity. 

 Copper does not oxidize as readily as iron 

 and is not lost. The world's stock steadily 

 accumulates. But twenty years is not a 

 long look ahead. Are there new countries 

 which will be producers ? Some of the old 

 mines in Europe are now no longer great 

 sources of the metal. 



