chap. xv. Metalliferous Veins. 581 



With respect to the distribution of the different metals, 

 copper, gold, and iron are generally associated together, 

 and are most frequently found (but with many ex- 

 ceptions, as we shall presently see) in the rocks of the 

 lower series, between the Cordillera and the Pacific, 

 namely, in granite, syenite, altered feldspathic clay- 

 slate, gneiss, and as near Guasco mica-schist. The 

 copper ores consist of sulphurets, oxides, and carbon- 

 ates, sometimes with laminee of native metal : I was 

 assured that in some cases (as at Panuncillo SE. of Co- 

 quimbo) the upper part of the same vein contains oxides, 

 and the lower part sulphurets of copper. 1 Gold occurs 

 in its native form ; it is believed that, in many cases, 

 the upper part of the vein is the most productive part : 

 this fact probably is connected with the abundance of 

 this metal in the stratified detritus of Chile, which 

 must have been chiefly derived from the degradation of 

 the upper portions of the rocks. These superficial beds 

 of well-rounded gravel and sand, containing gold, 

 appeared to me to have been formed under the sea 

 close to the beach, during the slow elevation of the 

 land : Schmidtmeyer 2 remarks that in Chile gold is 

 sought for in shelving banks at the height of some feet 

 on the sides of the streams, and not in their beds, as 

 would have been the case had this metal been deposited 

 by common alluvial action. Very frequently the 

 copper-ores, including some gold, are associated with 

 abundant micaceous specular iron. Gold is often 

 found in iron -pyrites : at two gold mines at Yaquil 

 (near Nancagua), I was informed by the proprietor 

 that in one the gold was always associated with copper- 

 pyrites, and in the other with iron-pyrites : in this 



1 The same fact has been observed by Mr. Taylor in Cuba • 

 •London Phil. Journ.' vol. xi. p. 21. 



2 ' Travels in Chile,' p. 29. 



