5 



is black;, but 9,0 filled with meialllc partlcks as 

 ^o have a ^vhitish appearance ; the two next 

 .strata are brovvn^ and arc caWedjnfilerias, the two 

 <;xterior ones are of a dark gre\% and known by 

 the name of brozas. Although the ;eneral di- 

 rection of tills Ycin is horizontal, it sometimes 

 runs perpendicular, and is found to increase in 

 richness in proportion to its depth. From assays, 

 which have been made at Lima on the ore of 

 Uspallata^, it appears that the guida yields more 

 than two hundred marks of silver the caxo?i ;* 

 the pint arias, mixed with the guida, fifty ; and 

 the Z^roca^' fourteen ; a produce not inferior to 

 that of the mine of Potosi. The mine of Us- 

 pallata was discovered in the year 16.38, but 

 although on its first discovery it furnished the 

 strongest indications of its wealth, from want of 

 labourers, or some other cause, it was neglected 

 until IT60, but since that period has been con- 

 stantly wrought with immense profit. 



Before the arrival of the Europeans, the In- 

 dians employed a very simple method to sepa- 

 rate the silver from the ore, especially when the 

 metal was in a metallic form, and not niineruiized 



A term nuub unc of by tlie American ni-etallurgisfs to ex- 

 press the cjur.nlit) ot" ore which a single miner cuu dig in a 

 (luy, usuallv cLilcLihited at fifty quintals ; hut, as tliis quaniity 

 Contains mure or less of the matrix, it is imposible to ascer- 

 tain the amount of pure ore contained in eacii caxon. 



