The Patio and Cazo Process. 8 



The minerals which arc usually found as ores, or associated 

 with them, are native silver, plata; kerargyrite, plata cornea 

 blanca ; embolite, plata cornea verde ; bromyrite, plata verde ; 

 iodyrite, plata cornea aniarillia ; argentite, plata negra ; ruby 

 silver, rosi clara ; arsenopyrite, ferro bianco; galena, plomo ; 

 and zinc blende, copelilla. 



The ores are generally distinguished as of two kinds, the 

 black, negros, and the colored, colorados. The former are 

 found in the lower part of veins, and comprise all the ores con- 

 taining sulphur. The colorados are found in the upper parts of 

 veins, and are composed generally of the iodides, bromides and 

 chlorides, with some native silver mixed with them. The gan- 

 gue is generally oxide of iron, carbonate of lime, or quartz ; oc 

 casionally some argillaceous schists which, when they are not 

 attacked by the reagents, can be as easily treated as the others. 

 This method is the only one that can be used in many places 

 in Mexico, on account of the high price of fuel. 



In some places, the very rich rebellious ore is roasted and then 

 treated, and this should always be done with all the negros when 

 fuel is not so dear as to render such a treatment impossible. 

 When the gangue is attacked to any extent this process cannot 

 be used. The works where these operations are carried on 

 are called haciendas. 



The process consists of five different operations : — 



1. Crushing the ore in a Chilian mill, California stamp, or a 

 breaker. 



2. Grinding and amalgamating the ore in an arrastra. 



3. Treatment on the patio. 



a. Making the torta. 



b. Introducing the reagents. 



c. Separating the amalgam. 



4. Treatment of the amalgam. 



5. Refining the silver. 



The following tree, prepared by Mr. R. E. Chism,* gives a 

 very accurate idea of all the details of the process. 



* Patio Process, San Dimas, Trans. Am. Min. Engs., Vol. XI, PL 1. 



