6 The ratio and Cazo Process. 



1. Ckushing the Oke. 



The amalgamating works consist of a large court, patio, sur- 

 rounded by sheds, galera, in which the apparatus for commin- 

 uting the ores is placed. All of the ore to be treated must be 

 reduced to an impalpable powder. The court is always paved 

 in some way, generally with stones; and if it is desirable that 

 it should contain only a single pile, is only 10 or 15 meters 

 square. "When a number of piles are made in the same enclosure, 

 it must be very large, as the piles are often 7 or 8 meters in dia- 

 meter. The court then would be 50 or 60 meters square, or 

 even larger. 



The ores are generally sorted according to their silver contents 

 and gangue, into three or four classes. At San Dimas* there 

 are four grades. The first is the lumps of pure ore picked out 

 by hand, metal hecho, or made ore, free from gangue, worth $400 

 or more to the ton. This is called metal de primera classe or 

 metal de exportation. The second is ore for the patio, called 

 metal de beneficio. It differs from the first only in being of less 

 value and by having gangue mixed with it. The third class 

 embraces the smalls from the hand-picking, and varies in 

 value according to the value of the ores from which it is selected. 

 It is called granza de llunque or tierras de llunque. The fourth 

 class comprises the smalls from the mine. It is mixed with much 

 gangue and dirt. It is called granza de labor es or tierras de 

 labor es. At Chihuahua,! where the ores are almost entirely com- 

 posed of native silver in a calcite gangue, they are separated into 

 three classes ; the first containing more than $2,500 to the ton ; 

 the second, more than $1,000 and less than $2,500; the third 

 class, under $1,000 and averaging about $250. 



This classification, however, differs at every works ; the first 

 consideration being always the value of the ore ; the second, 

 the kind and quantity of gangue, according as it may or may 

 not be attacked by the reagents ; and lastly, the size of the 

 pieces. 



* Patio Process at San Dimas. Trans. Am. Min. Eng. , Vol. XI. 

 f Rept. United States Mining Commissioner, 1874, p. 435. 



