Bisbee daily review., 1910-11-20
(Mining world.)


 } producing power of the United ! States. Waldemar Lindgren of the ] U. s. Geoogical Survey recently es timated that it was improbable that :, the United States coud make ar } output in excess of s110,00O,O00 pei ] annum. The United States coulC possibly maintain such a production ] for the next 20 years. It should be ! noted. however, that these estimates ,. were made from the basis of the i present condition of mining deve-op II ment and metallurgical processes | After 20 years Mir. Lindgren predicts that the gold production will gradual ly decrease
 There is probably, no individual | in the United States who has a wider knowledge of the conditions of pre- | cious-metal mining than MT. Lind. [ gren. He expresses his views care | fully and his opinions are certainly i entitled to great weight. We be- i ieve, however, that he has under | estimated the resources of the coun- try in precious metals, for it is not
 too much to expect that the west
 will be able to produce from S100.-
 oOo. .O00 to s150,o0O.O0O per annum
 for a great many years to come. We are on the eve of great | changes in precious-metal mining. | Tn mechanical aids to mining are developing at such a rate that ores. especially those in large veins will be brought to the surface at cost far below that at which they are now mined The development of
 water power, allowing the use of high grade electrical machinery. the | development of small hammer stoping machine, and the probability
 that a commercial tunneling machine will be development of the near | future. gives us the hope that the enormous masses of iow-grade ore, now having very little value, will be- | come a source of profit and hence will be mined, Then, too, there IS every reason to believe that new processes peculiarly adapted to the treatment of complex ores will be developed. Lastly. there can be no doubt that. new mining districts will i be discovered that will greatly aug ment the production of gold in the near future
 For many years previous to 1892 the annual production of god was almost uniform. standing at about 8 900 .Oo0, 900 per annun. However. in 1892 after 30 years of persistent prospecting around Pike's Peak, Cripple Creek was found and the production of Colorado rapidly in- creased, until it produced almost as much gold as all the rest Of the United States prior to 1892.
 After the repeal of the sherman Act. the miners in districts which had been regarded as almost entirely siiyer-bearing, began to have their ores assayed for gold. with the re- suit that those districts are now producing gold very heavily. Thus the "Silvery San Juan" became misnomer, for that region of Colo rado is now c very important gold producer.
 About the same time the introduc- ton of the cyanide process revolu- tiouized the metallurgy Of gold ores. and mines which had been closed down through lack of ability to ab- stract the values of the ore were reopened and became once more important producers. !,
 Indeed, the Rocky mountains and
 Sierra Nevadas have been but bare ly scratched. New districts no doubt
 will be discovered in the next 10 years that will rival Cripple Creek and Goldfield This is a matter of opinion. of course, but there Is an other field which is an important factor. about which only one opin- ion can be he'd. We allude to the enormous masses of low-grade com plex ores carrying gold and silver values that exist in nearly every old mining camp in the west Tnese ores are merely awaiting commercial processes for the extraction of the
 values. This is one of the most important problems before the scien- tific men of the world today and the urgency of the demand Is bound to bring a solution of the problem for science has never yet failed to meet the requirements of commerce. When these processes are furnished the miner, the the old mining camps will add many millions to their an- nual production of gold and silver.
 It has often been said that the
 mines are becoming poorer with depth. While this statement is true in some particulars. yet like most rules it has its exceptions and mod ifiications. In many districts the ores have merely changed in char
 acter, but still have an intrinsic
 value equal to the surface ores. For example. the average grade of the surface ores of Leadville could not have been much over s35 a ton be- tween the years 1880 and 1895. To day in the lower levels of that dis trict there are enormous tonnages of ore which when one considers all