286 SALAJIANCA. 



Cosola, Zolaga, and Sombrcte. The mine of la Yeta 

 Negra, near Sombrete, yielded in five or six months 

 seventy thousand silver marcs ; yet it was not one hun 

 dred feet deep. Black silver was common in the mines 

 of Guanaxuato, Zacatecas, and Keal del Monte. Muri- 

 ated silver abounded in the mines of Catorce, and Cerro 

 San Pedro. At Fresnillo it was frequently olive-green ; 

 superb samples of this colour were found in the mines 

 of Yallorecas. The veins of Zimapan, a little to the 

 north of Keal del Monte, offered a great variety of 

 curious minerals ; among others chrysophrase, and a 

 new species of opal of rare beauty. Humboldt procured 

 one of these opals of great size, and carried it with him 

 when he returned to Europe. The mineralogists Karsten 

 and Klaproth described it as a fire-opal. 



Of all the rock-formations in Mexico the porphyritic 

 rocks were the richest in gold and silver ; then came 

 primitive slate, graywacke, and alpine limestone. Cop- 

 per was found in the mines of Ingaram, and at San Juan 

 Guetamo. Tin was sometimes obtained by washing the 

 alluvial lands. Iron, too, was abundant. 



From Guanaxuato Humboldt proceeded in a southerly 

 direction to Salamanca. He stopped at Salamanca long 

 enough to fix its latitude and longitude, and then con- 

 tinued his journey to Yalladolid, the capital of the In- 

 tendancy of that name. Yalladolid was a small city, 

 containing only eighteen thousand inhabitants. Its ele- 

 vation was six thousand four hundred feet above the sea, 

 yet snow had been known to fall in its streets. It con- 

 tained nothing worthy of notice, except an aqueduct, and 

 a bishop's palace. 



From Yalladolid he proceeded to Pascuaro. 



