Model of an Arizona Gold Mine 9 



above the drift. Here a narrow niche has been exca- 

 vated to the side of the drift and a raise has been 

 driven a few feet into the ore of the roof. A miner 

 may be seen blasting out the beginning of a stope above 

 this raise. Between this and the shaft appear two 

 stopes in operation. These two have in the progress 

 of the work run together, making one large stope. 

 There are many ways of conducting mining operations 

 in a stope and the methods employed must be adapted 

 to the conditions in the mine. The method employed 

 here is called shrinkage stoping and the stope is a 

 SHRINKAGE STOPE. The ore is blasted from the 

 roof and allowed to lie on the floor of the stope. As 

 the broken ore occupies more space than it did when 

 unbroken, if all were allowed to remain it would more 

 than fill the stope. It is therefore drawn off from 

 time to time from below but leaving enough behind so 

 that miners standing on it may reach the roof con- 

 veniently. Standing on this broken ore they drill 

 holes in the ore above them, using for the purpose a 

 special type of air drill, called a stoper. The com- 

 pressed air for these drills comes from an air com- 

 pressor on the surface in a small building behind the 

 shaft. It is led down the shaft and along the drifts 

 in metal pipes. From these pipes it is conducted to 

 the drills in the stopes by rubber hose. When the 

 proper number of holes are drilled they are loaded 

 with dynamite and after the men have left, the holes 

 are fired, breaking more ore. In a small stope on the 

 lower level, the holes have been loaded and a miner is 

 preparing to light the fuses. The excess ore is then 

 drawn from below and the operation repeated. Access 

 to the stope is by a manway with ladders which is kept 

 open through the broken ore by timbering. At the 

 bottom of the stope near the entrance of the manway 

 is a chute equipped with a gate through which the ore 

 is drawn off into ore cars in the drift below. These 



[9] 



