230 Principal Silver Mines in Mexico and South America. 



Comparison^of the expense and profit of the mine of Valenciana, 

 in Mexico, and Himmelsfurst, in Saxony. 



Mine of Valenciana. Mine of HimmelsfuTSt. 



Quantity of silver, - - 360,000 marcs. 10,000 marcs. 

 Total produce, - - $4,600,000 |66,000 



Expenditures, - - - ^1,000,000 ^48,000 



Net profit, - ' - - 1600,000 |18,000 



Quantity of silver, per quintal, 4 ounces. 6 to 7 ounces. 



Number of workmen, - 3100 700 



Do. do. in the riiine, 1800 550 



Value of one day's labor, |1 to |1.20 |0.18 



Expense of powder, |80,000 |5,400 



Quintals of ore sent to the ) 7^0,000 14,000 



amalgamation works, ) . 



Depth of the mine, 1650 feet. 1050 feet. 



The proprietors of Valenciana receive, then, a profit of 37|- per 

 cent, on the gross receipts of the mine, while at Himmelsfurst the 

 profit is only 27 per cent. 



II. Zacatecas, Fresnillo, Sombrerete, and Catorce. 



The district of 2^acatecas is situated to the north west of Guan- 

 axuato, to which, in its geological constitution, it is, in many respects, 

 analogous. The veins are explored in the grauwacke, and are found 

 to be richer upon the highest and most barren summits, than upon 

 the declivities, or in the ravines and valleys. 



The principal ores are sulphuret of silver, native silver, red silver, 

 black silver, chloride of silver, argentiferous galena, carbonate of lead, 

 sulphuret of zinc, pyrites, pyritous copper, carbonate of copper, sul- 

 phuret of antimony, and native gold. The principal secondary rocks 

 of Zacatecas are compact limestone, siliceous slate, " gres ancien," 

 containing fragments of granite, and an argillaceous feldspathic con- 

 glomerate. Both these last are different from grauwacke** Argil- 

 laceous slate and porphyry are also observed. 



The district of Fresnillo bounds that of Zacatecas on the north 

 west, and its mines are also situated in grauwacke. The veins of 

 chloride of silver are very numerous. The ore is generally of a green 

 or gray color. 



* "Tous deux differens de la grauwacke." Ann. des Mines, t. xxxi, p. 331. 



