MINERALS OF CHILE. 



The minerals collected by the United States naval astro- 

 nomical expedition were almost exclusively those of silver and 

 copper. The specimens of the ores of these two metals, taken 

 in connection with all authentic accounts, would lead one to 

 believe that Chile hardly has a parallel in any region in the 

 globe for the abundance as well as purity of these ores. Were 

 it not for the physical difficulties connected with the surface of 

 the country, and the scarcity of water and fuel, the wealth 

 accruing to Chile from the working of these mines would be 

 far greater than it is now. 



Although the expedition furnishes no geological report of 

 the country, it is thought proper, before describing the min- 

 erals in detail, to give some general idea of the geology of the 

 country, more especially as connected with the minerals col- 

 lected; and for this purpose recourse is had to the labors of 

 M. Domeyko and M. L. Crosnier, as published in the "Annates 

 des Mines." 



A general idea of the geological structure of Chile is readily 

 formed, although we might be led to suppose otherwise from 

 the great disturbing forces that have operated in that part of 

 the world in the form of injected masses of igneous rock, as 

 well as from the present changes produced by existing volcanic 

 action, and the gradual elevation of the whole country, with 

 daily recurrence of earthquake action. These disturbing forces 

 do not, however, in any way interfere with our study of the 

 general geology of the country, while of course it renders the 

 investigation of the geology of any particular region exceed- 

 ingly embarrassing. 



The great chain of the Andes extends parallel to the coast 

 of Chile at a distance of from ninety to one hundred miles. 

 On the eastern side it descends by gradual slopes toward the 

 immense plains of the Argentine Eepublic. On the western 



