372 ANAALS NEW YORK ACADEMY OF SCIENCES 



metallic contents which it contains. We can thus gain an idea of the 

 close and economical work required and the ability demanded of a man- 

 ager. As the price rises, the profits greatly increase, and temporarily idle 

 mines are brought within the widening remunerative zone and are quick- 

 ened into life. As the price falls, the mines dangerously near the line 

 close down and production ceases. The lowest cost of production claimed 

 is from the low grade and very large ore bodies of the west and is placed 

 at or about eight to nine cents per pound laid down in Xew York. 



In copper ores outside of the Lake Superior region, we usually find the 

 metal in composition with sulphur. The ores as they come from the mine 

 may be rich enough to go directly to the smelter, or they may require con- 

 centration before the grade is sufficiently high. The ores which are directly 

 smelted reach the minimum of copper in the Boundary district of British 

 Columbia, 1)ut associated gold and silver raise the value per ton above 

 four dollars. Copper ores yielding copper alone were smelted at Duck- 

 town, Tenn., during long campaigns at a little less than 2.5 per cent. In 

 earlier years and in many mining districts, 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 standard of comparison. What is the outlook for the future of 

 copper production ? 



We can not predict copper with the certainty of iron. It seldom ap- 

 pears in bedded 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 complete 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 become the ores of to-day. Where we find in porphyries 

 or schists copper sulphide disseminated in fine particles or as coatings 

 along crevices and in sufficient richness 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 surface, steam shovels make excavation extremely 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 begins, 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 



