REPORT ON THE MINERALS OF CHILE. 



BY J. LAWEENCE SMITH, 



PROFESSOR OF CHEMISTRY OF THE MEDICAL DEPARTMENT, UNIVERSITY OF LOUISVILLE. 



The minerals collected by the United States naval astronomical expedition were almost 

 exclusively those of silver and copper. The specimens of the ores of these two metals, taken 

 in connexion 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 tlie 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 minerals in detail, to give some general idea of the geology of the coun- 

 try, more especially as connected with the minerals collected; and, for this purpose, recourse 

 is had to the labors of M. Domeyko and M. L. Crosnier, as published in tlie " Annales 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 investiga- 

 tion of tlie geology of any particular region exceedingly embarrassing. 



The great chain of the Andes extends parallel to the coast of Chile, at a distance of from 90 to 

 100 miles. On the eastern side it descends by gradual slopes towards the immense plains of the 

 Argentine republic. On the western side, where the upheaving force appears to have concen- 

 trated all its energy, the slopes are abrupt, and transformed frequently into vertical precipices 

 of considerable height. The mountains appear heaped confusedly one on top of the other, and 

 the first impression is, that, in the midst of so much confusion, it is vain to seek for the primi- 

 tive condition of the surface of Chile. Stratified rocks disappear entirely from north to south 

 for the mean width of 45 miles — from the desert of Atacama to Valdivia. These rocks, 

 although they once existed, are now profoundly altered or entirely melted by contact with 

 the enormous masses of granite. The clay shales, which doubtless constituted the mass of 

 the original stratified rocks, are now transformed into porphyries of every shade and of the 

 most varied composition, alternating, in some parts, with beds of compact quartz. Even when 

 the rocks are seen stratified, far removed from the masses of granite, and in beds sensibly 

 horizontal or little inclined, still the numerous injected veins which traverse them, and ramify 

 in all directions, prove that hardly anywhere have the rocks escaped the modifying force of 

 igneous action. 



