Bisbee daily review., 1904-05-05
Lake Superior
 COPPER, TOLD BY Horace Stevens
GREAT CHANGE IS NOW BEING MADE IN THE PRO-
 DUCTiON.
Ore Reserve at Calumet and Hecla Variousy Estimated at Ten to Thirty Years-Talk of Shaft Two Miles Deep. .

Houghton. Mich. May 4.-(Special to the Review. )-The old order changes and a critical observer, well acquainted, with the past history of Lake Superior copper mining, can note the great change that is now be- ing made in the production of the dis trict With rare exceptions the old mines are marking the time for going backwards. while the younger and more vigorous properties are gaining ground. That this should be so is not surprising, for the richest mine has it's bottom, but it comes as something of a shock to the old residents, ac- customed for a generation or more to consider the great mines as immortal. It should not be inferred, however, from the preceding statement, that the old and large mines of the dis trict are in danger of immediate ex- tinction, or that their arrangements have grown senile. Such fine old mines as the Calumet & Hecla and Quincy will last for another generation at least, and discoveries of parallel cupriferous beds may proiong their life indefinitely. In the case of the Calumet & Hecla such prolongation. due 10 the opening of new mines is reasonably well assured and the Quincy amygdaloid. The improvement in methods and machinery has been marked curing the past decade, and every item of rock manipulation has been materially reduced. For this req son it is possible to mine and mill much lower grade rock than ever be- fore, and some of the experiencing amygdaloid and conglomerate beds, pronounced worthless after exhaustive tests made many years ago, will even tually be worked at a profit. It is this possibility of developing parallel mines that gives hope for the remote future of the great old mines of the district that have reached their apogee.
 The ore reserves of the Calumet & Hecla are variously estimated at ten to thirty years. The former figure is much too low, as the mine has ground opened ahead of the stcping parties for nearly that length Of time. while the higher figure is based upon desires and hopes, rather than on tangible measurements and estimates. By yirtue of lower costs in mining and milling, the Calumet & Hecla can now work lower grade rock than ever before, and the limit has not yet been reach ed in this regard. The mine. however, has physical limitations, and while its territory west of the Tamarack un- doubtedly carries the undeIlay of the Calumet conglomerate reef, the disap- pointingly low returns of copper given by all four of the deep vertical shafts sunk on the underfay of the con- glomerate. three by the Tamarack and one by the Calumet & Hecla, renders it reasonably certain that at still great CT depths the reef would prove still leaner, hence there is little likelihood that the Calumet & Hecla manage ment will ever attempt to sink a two mile shaft to reach the conglomerate west of the Tamarack. The objection to such, which has been given fena- tive consideration, are many and seri- ous. As to time. not less than ten years would be required for sinking, and longer period might be needed. The cost of sinking the shaft and equipping it with adequate hoisting macn1nery, cOmpreSsOrS anu Toch- houses. would be not less than five millions of dollars, and perhaps nearly twice as much. The heat of the mine openings at a depth of two miles would preclude work, except by the aid of artificial ventilation on a very ex- tensive scale. and it might be neces- sary to reinforce this by artificial re- frigeration. Last, but by no means least, the conglomerate might be found pinched 10 unavoidable dimen- sions. or possibly, cut out entirely, though the latter contingency is a possibility rather than a probability, and the copper contents of the rock would, in all likelihood, be very low.
 The percentage of copper secured per ton of rock crushed is steadily de- creasing at all of the old mines of the district. This is true of the Calumet & Hecla. Tamaraek and Quincy and the Atlantic is the only old property affording the p-overbial exception needed to prove the rule.
 HORACE STEVENS.