56 MINERALS OF CHILE. 



porphyry of a great variety of shades of color. Sometimes 

 the porphyry is entirely altered ; it then contains well-formed 

 crystals of feldspar, and appears to have been melted where it 

 now rests ; and at other times it is earthy, as if the transfor- 

 mation had been incomplete. Large masses of reddish, yellow, 

 and violet quartz alternate with the porphyry in certain 

 points ; also calcareous beds, sometimes fossiliferous. These 

 stratified rocks are elevated on the flanks of the Andes, and 

 form some of the most prominent peaks of this range. These 

 strata are so completely pierced and elevated in every direction 

 by the masses of granite as to modify in every possible manner 

 their direction, inclination, and mineralogical character. 



Besides the secondary stratified rocks just made mention of, 

 there are other stratified rocks which are horizontal, having 

 been deposited since the elevation of the mountain-chains. 

 They are all, however, of recent origin and of small extent, 

 disseminated along the coast, with the exception of the sandy 

 plain that extends between Huasco and Copiapo, having a length 

 of from one hundred and twenty to one hundred and thirty 

 miles, with a variable width. This plain has, however, been 

 elevated since its formation; in fact, M. Domeyko has deter- 

 mined three distinct terraces of successive and gentle elevation. 

 There are also alluvial deposits now going on in some of the 

 valleys of the elevated portions of the mountains, consisting 

 of a fine clay, transported there by the mountain streams. 



According to the observation of M. Crosnier, he has en- 

 countered but one formation that appears to be of lacustrine 

 origin, and this is situated in the Cordilleras of Chilian, forty- 

 five miles north of Lavederos. 



The tertiary deposits subsequent to the elevation of the 

 Andes contain in many parts lignite. Some of these places 

 are worked. The principal mines are situated to the south of 

 Biobio, some twenty miles distant from the mouth of this river, 

 on the sea-shore. The mines are called Lota and Lotilla. 



Some of the departments of Chile have been examined with 

 minuteness by M. Domeyko, more especially that of Copiapo; 

 which, although little else than a vast desert, is the richest 

 department of Chile in mines of every description, there not 

 being a single mountain where the veins are not of sufficient 

 importance to be worked. And it is worthy of remark that 



