392 METALLIFEROUS DEPOSITES. 
VIII. INTENDANCY OF VALLADOLID. 
éo- Angangueo. 30. Zitaquaro. 
34, Inguaran. 36. Tlalpajahua. 
IX. INTENDANCY OF OAXACA. 
o7. Oaxaca. 
X. INTENDANCY OF PUEBLA, 
Several Mines. 
XI. INTENDANCY OF VERA CRUZ. 
Three Mines. 
XII. OLD CALIFORNIA, 
One Mine. 
In the present state of the country the veins are 
the most productive, and the minerals disposed in 
beds or masses are very rare. The former are chiefly 
in primitive or transition rocks, rarely in secondary 
deposites. In the Old Continent granite, gneiss, and 
mica-slate, form the central ridges of the mountain- 
chains; but in the cordilleras of America these 
rocks seldom appear externally, being covered by 
masses of porphyry, greenstone, amygdaloid, basalt, 
and other trap-formations. The coast of Acapulco is 
composed of granite; and as we ascend towards the 
table-land of Mexico, we see it pierce the porphyry 
for the last time between Zumpango and Sopilote. 
Farther to the east, in the province of Oaxaca, gra- 
nite and gneiss are visible in the high plains which 
are of great extent, traversed by veins of gold. 
Tin has not yet been observed in the granites of 
Mexico. In the mines of Comarya syenite contains 
a seam of silver ; while the vein of Guanaxuato, the 
richest in America, crosses a primitive clay-slate 
passing into talc-slate. The porphyries of Mexico 
are for'the most part eminently rich in gold and 
silver. They are all characterized by the presence 
of hornblende and the absence of quartz. Common 
