8 Geological and Miscellaneous Notice of Tarapaca. 



The cost to the refiner for labor, for each one hundred and two 

 pounds, is about five reals, or 62| cents ; for fuel, from two and a 

 half to three reals ; for powder and tools, about one real ; and 

 for transportation to the port, from five to six reals; making in all 

 $1 87£, which is probably something more than the average cost 

 of nitrate of soda, exclusive of bags for packing, and the expense 

 of constructing, keeping in repair, and superintending the estab- 

 lishment. 



Ores of silver, antimony, and copper, are found in the porphy- 

 ritic hills on the coast — the two former near Iquique, in exten- 

 sive veins, the latter in inconsiderable quantity near Pisagua and 

 in the vicinity of Tanna. Copper also occurs at the extreme 

 southern and eastern part of the province, in veins traversing feld- 

 spar. The ores are sulphurets, carbonates, and muriate. In the 

 same range of hills, a little further south, and without the limits 

 of the province of Tarapaca, this latter ore has been found in 

 such quantity as to give rise to extensive workings. It is pro- 

 cured by the Indians, and sold, under the name of arenilla, as 

 sand for letter writing. 



The silver mines of Guantajay and Santa Rosa, near Iquique, 

 were formerly extensively worked, and have yielded a large 

 amount of silver ; but of late years, owing to the increased ex- 

 penses of mining and the poor quality of the ore obtained, most 

 of the workings of the former, and many of those of the latter, 

 have been abandoned. The mines, at the time when I visited 

 them, did not yield ore containing in the mass more than 0.31 per 

 cent, of silver ; but they formerly yielded an abundance of rich 

 ore, and have afforded some of the largest and purest masses of 

 native silver which have been found. In 1758 and 1789, two are 

 said to have been discovered here, the one weighing eight hundred 

 and the other two hundred pounds. Native and horn silver are 

 still often extracted, but it is from the antimonial silver ores that 

 the principal profit is derived. A mixture of chloride, sulphuret 

 and native silver, mixed with galena and accompanied by quartz, 

 is found in some small veins. The matrix is generally carbonate 

 of lime, and the veins vary in width from a size barely percepti- 

 ble to more than a foot. 



The observed temperature of the air at the bottom of the work- 

 ings, in the mines of Santa Rosa, was 98° Fah. That of the 

 air at the surface, at the same time, was 84° Fah. 



