M1NEEAL0GY OF CHALANCHES. \Qf 



not continue for any considerable length ; and they expe- 

 rience the same accidents. Their richness, direction, in- 

 clination, thickness, &c, are continually varying. They 

 are incessantly intersected, turned aside, choaked, and in- 

 terrupted by the veins. Finally, as they appear to owe 

 their formation to the same cause as produced and formed 

 the veins after the rupture and convulsions of the mountain, 

 and the filling up of its clefts, I am induced to consider 

 them rather as horizontal veins, than as real beds. 



Sometimes the ore occurs in nodules, but less frequently Nodules* 

 than in veins, and like these they vary both in richness and 

 magnitude. 



Their gangue is still more varied. Most commonly it is Gangue very 

 carbonate of lime, pure, mixed, associated, crystallized, yarious ' 

 amorphous, &c. Sometimes it is sulphate of lime; in other 

 places it is flexible asbestus : frequently it is hyaline quartz, 

 pure, mixed, crystallized, amorphous, &c. : occasionally it 

 is argilaceo-calcareous : here it is green or brown pulveru- 

 lent chrolite talc, and yonder the same in mass containing 

 native silver: frequently it is epidote in mass or crystallized : 

 &c. Among the metallic gangues we find oxide of cobalt Metallic gan- 

 both earthy and vitreous, arsenicated, arsenical, and gray S ues » 

 cobalt, all of them more or less argentiferous. Arsenical 

 and carbonated nickel frequently perform the office of a 

 gangue, and sometimes the first of these is even rich in sil- 

 ver. Arsenic too is found in the argentiferous ores, but it is 

 more rare than the preceding. Antimony occurs native, 

 sulphuretted, oxided, and as a hidrosulphuret. Copper, 

 which is very abundant in the veins, is met with in different 

 states: pyritous, sulphuretted, oxided, and hidrosulphuret- 

 ted. Gray copper ore is frequently found in the asbestus, 

 and always very rich in silver. Iron and manganese, both 

 in the state of oxide, occur very commonly in the veins at 

 Chalanches: and the latter is even one of the richest 

 gangues in silver. Lead is found as a sulphuret, and some- 

 times phosphated. Mercury too is found in the gangues at y, &r 

 Chalanches, and frequently is even abundant in them. 



Above the silver mines we find two narrow valleys, one o£ Valleys. 

 which runs east, the other west. These narrow gradually to 

 the foot of the highest peaks. 



The 



