22 GEOLOGY. 



The working of these mines is carried on in a very rough manner. The excavations simply 

 commence with the surface exposure of the veins, thence following them down by rude and 

 irregular shafts, inclined according to the dip of the vein, at an angle of 45° to the northwest. 

 The ore is extracted hy blasting, both the mineral and the refuse material being brought up on 

 men's backs. Where the depth is such as to cause an accumulation of water the mine is 

 abandoned. 



The richest of these distinct mining excavations is that called ^' San Pedro." This, when 

 visited in 1852, had attained a depth of eighty yards. The mineral vein, as exposed along the 

 line of excavation, exhibited a very variable thickness, from one to twelve inches ; the character 

 of the ore and its specific gravity also varied at different points. — (See description and analysis 

 by Professor T. Antisell.) 



The mode of extracting the silver is by a double process of smelting and refining. By the 

 former the ore is reduced, by the means of a common furnace, to the form of an alloy of lead 

 and silver. In the refinery the lead is removed by burning it out in a blast furnace, leaving 

 the silver in the shape of irregular cakes, weighing about eight ounces each. The refining 

 process occupies about twelve hours. 



The following information in reference to the working of two of the principal mines and 

 reducing establishments and the amount of silver produced is furnished by the proprietor, 

 Mr. Luis Flotte, of Baranca. 



The mine of San Pedro employs about forty men, whose wages average $10 per month. The 

 amount of ore extracted by this number of men monthly is from 160 to 200 loads, of 300 pounds 

 each. This is calculated to yield from 24 to 32 ounces of silver per load. The average monthly 

 expense of working this mine is about $1,000. 



The mine of Leon employs about the same number of men, and requires the same expense of 

 workin"", vi^: $1,000 per month. The amount of mineral extracted from this mine is about 

 500 loads per month, of 300 pounds each, estimated to yield three ounces of silver to the load. 

 This ore is chiefly valued as a flux to assist in the reduction of the richer mineral. 



Smelting Establishments and Refineries. 



There are two of each of these establishments in operation at Baranca. The number of men 

 employed in all the necessary labor, including hauling the mineral, manufacture of charcoal, 

 &c., is 125. The average monthly expense is $2,000. 



When in full operation, the amount of ore smelted is 180 loads of San Pedro ore, and 500 

 loads of Leon mineral, of 300 pounds each. Total, 204,000 pounds per month. 



The yield of silver for tbis amount of ore would be an average of 420 pounds, at $16 per 

 pound, equal to $6,620, leaving a profit for capital invested of $2,620 per month. The total 

 amount of silver produced at this mining location for six years ending January 1, 1852, as given 

 by the two proprietors, is — 



Mr. Luis Flotte, at Baranca $340,000 



Senor Don Jose Maria Zuloaga, at Coralitas , 146,000 



Total 486,000 



