CHILI. 201 
veins in the claystone and the rock of this dike, but most abundantly 
near the junction of the two rocks. The veins are very irregular, 
and are more or less elongated. They are occasionally connected, 
but in the excavations frequently run out. In order to discover 
new ones, they follow the lines of the green carbonates, or the 
seams of calcareous spar and quartz. The name of metal is given 
as a general term to all the ores, that of quizo to the lode in which 
they are contained. 
The ores contain more or less sulphur, and often a portion of 
arsenic. Some silver is also occasionally mixed with the copper. 
Some of the ores found at this mine have been very rich, yielding 
sixty-five to seventy per cent, of pure copper. The average yield is 
about forty-five per cent. The various qualities are denominated, 
metal-regio, platiado, bronze, and piedra bruta. The last, as the name 
implies, is worthless. 
The mines, by the light of the numerous candles, exhibited all the 
shades of green, blue, yellow, purple, bronze, &c, having a metallic 
and lustrous appearance. The confined air, with the heat of so 
many candles, made it quite oppressive, and persons who have not 
often visited mines, are subject to faintness and vertigo. Mr. 
Alderson and Mr. Dana were both affected by it. It was the first 
time the former had ever penetrated so far, Mr. Newman and himself 
being governed by the report of the mayoral, and the ore brought up 
in their operations. The miners were not a little astonished at our 
gentlemen loading themselves, besides the specimens of ores, with 
the piedra bruta which they considered of no value. The manner of 
labour in the mines is in as rude a state as it was found in the agri- 
cultural branches of industry. A clumsy pick-axe, a short crowbar, 
a stone cutter's chisel, and an enormous oblong iron hammer, of 
twenty-five pounds weight, were the only tools. The hammer is only 
used when the ore is too high to be reached with the pick or crowbar. 
The miners, from the constant exercise of their arms and chest, have 
them well developed, and appear brawny figures. When the ore is 
too tough to be removed by the ordinary methods, they blast it off in 
small fragments, not daring to use large blasts, lest the rock should 
cave in upon them. Only a few weeks previous to their visit, the 
mayoral, while at the farthest end of the gallery, was alarmed by the 
rattling down of some stones, and before he could retreat, the walls 
caved in for several yards outside of where he was, leaving but a 
VOL. I. 51 
