METALLIFEROUS MINING 215 



done much to remove, once and for all, the wasteful 

 and uncertain methods on which we relied pre- 

 viously. 



The Metals. 



Owing to the usual mode of occurrence of 

 metalliferous minerals, their mining is fraught with 

 increased difficulties. They occur as irregular 

 masses in association with igneous rocks and in 

 various ways which cause them to present a set of 

 problems quite distinct from those of the stratified 

 deposits. But the geologist by a thorough investi- 

 gation of our own and foreign mineral-deposits has 

 been able to establish a series of laws, and to 

 formulate a number of working theories, that have 

 had a profound influence on the methods of pro- 

 specting and on modern mining in general. 



The structural difficulties encountered in metalli- 

 ferous mining, such as the pinching-out of veins, 

 their faulting, and other disturbances to which 

 metalliferous deposits are prone, are those which 

 can only be met and overcome by a knowledge of 

 geological principles; but it is particularly in 

 relation to the mode of occurrence of metalliferous 

 deposits that geology has rendered the greatest 

 service. With the introduction of precise petro- 

 logical methods, geologists were equipped with 

 another weapon with which to attack a number of 

 problems of which there appeared to be no definite 

 solution. By its use the geologist was enabled to 



