54 Skeich of the Mine of Pasco. 
heights of Tulluranca, in the chain of Alconoculpan, lake of Huisque 
and Huarochiri. In all the rugged land which surrounds the ledge, . 
as in the pampas of Bombou, the highlands of Pargas, Vinchos, 
Cuypan, Vruda, &c. this formation is visible and extensive ; the gres 
is red, with yellow and. white spots; its grain is fine, rough to the 
touch, and passes insensibly to the white, and argillaceous earth alter- 
nating with strata of compact, white and blue limestone, and red and 
green porphyry. In this sandstone or red. gres, has been found in 
small quantities, the cinnabar, near the tenements of St. Lovergo, 
which is not strange, because the soil is just like that of Cuypan, and 
lies in the same direction. This gres is varied by a darkish esquito, 
in the strata, of small bulk, with limestone full of shells, (height of la 
Vinda,) and with a cuarzolidio or touchstone, (chain of Colquijuca.) 
From the center of the mine, some promontories of a quartzose rock, 
full of cavities, rise up, of a yellowish color, like the ochre of iron; 
within it is of a dirty white, with a conchoidal fracture ; it passes in 
some pieces to flint, but its qualities indicate it to be a quartzose por- 
phyry, (hornstein.) Many fragments, and other pieces extracted 
from one of the sky lights of the excavation, show the pudinga, (pud- 
dingstone or conglomerate,) distinguished by iron pyrites and white 
quartz. ‘This composes all the hill of St. Catalina, hills of Yaua- 
chancha, Chaupimarca, Caya, St. Rosa, Fraguarmachay, and ex- 
tends to Ayapota, &c. In the interior of the mines, it passes toa 
decomposed gres, as in the mines of St. Augustin, Descubridora, the 
great mine of the Tjarras, of Tingo, &c.-the grain of which is loose, 
is not as hard as that of the former, and is more mixed with the ox- 
ide of iron. This rock is the gangue of metals known by the name 
of pacos, which compose all the soil of St. Rosa. Here no stratifi- 
cation is perceptible on the surface, nor in the interior ; it is nothing 
more than a shapeless mass of metals extracted in abundanee, with- 
out the necessity of gunpowder. Thousands of loads are here found, 
about five or six marks in value, which do not defray the expenses, 
when the quicksilver is dear. The metals exploded in the mines 
which haye been mentioned, are extracted from a very distinct stra- 
tum, which is found decomposed in this rock, and another of pyrites. 
There is a dispute whether it is really a stratum or a vein ; the miners 
commonly call it a vein, and Trevithich, a miner and engineer of 
Cornwall, who was some years in the mine, has fallen into the same 
mistake. No quality or sign favors this supposition. 
“ 
