106 CRUISE OF THE BARRERA 



The first faulting opened up the formation and 

 resulted in a slight mineralization through the deep- 

 lying serpentines below. The second movement 

 refractured and fissured the formation, and at that 

 time the heavy mineralization occurred. The third 

 reopened, fractured, and further faulted the strata 

 and permitted of a renewed enrichment of mineral. 

 These various movements which opened fissures 

 through which the mineral welled up and replaced 

 the sandstones and impregnated the adjacent strata 

 with copper salts, have left a very complicated series 

 of faults for the mining engineer to contend with. 

 His first problem is to chart the slips and verti- 

 cal changes. Mr. Morse conducted us through 

 the main tunnel pointing out the fault evi- 

 dences and demonstrating how a disappear- 

 ing ore-bed can be relocated, without the hazard 

 of guesswork. Typical analyses of the mixed 

 sulphide copper ores from the mine show : 



