196 CHILL 



copper (chrysocolla), stain the rock for one hundred feet from the 

 vein, occupying the fissures, and giving the surface a green or bluish 

 tinge. In some places chrysocolla forms in small botryoidal incrusta- 

 tions on the face of the rock. The ores of copper occur in 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 excava- 

 tions 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 from this cause. 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 w r ere 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 agricultural 

 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 

 wen 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 



