398 
tiired part could be seen only by putting it in a 
vertical position. When Cortez destroyed the 
temples, he broke the idols, and every thing that 
belonged to the ancient rites. Those masses of 
stone, which were too large to be destroyed, were 
buried, in order to conceal them from the eyes of 
a vanquished people. Though the circle, which 
contains the hieroglyphics of the days, is only 
three metres four decimetres in diameter, we 
found, that the whole stone formed a rectangled 
' parallelopipedon of four metres length, as many 
metres broad, and one metre thick. 
The nature of this stone is not calcareous, as 
Mr. Gama asserts ; it is a blackish gray trap- 
pean porphyry, with basis of basaltic wahke. 
On carefully examining some detached frag- 
ments, I perceived hornblende, several very 
slender crystals of . vitreous feldspar, and, what is 
very remarkable, sprinklings of mica. This 
rock, cracked and full of small cavities, is desti- 
tute of quartz, like almost all rocks of trappean 
formation. As its actual weight is more than 
twenty-four tuns, and no mountain within eight 
or ten leagues of the city could furnish a por- 
phyry of this grain and color, we may easily ima- 
gine the difficulties, which the Mexicans musl^ 
have found in transporting so enormous a mass 
to the foot of the Teocalli. The sculpture in re- 
lievo is as well polished as any other to be found 
in Mexican works ; the concentric circles, the 
