224 GEOLOGY OF TRANS-PECOS TEXAS. 



El Paso smelters is prepared to reduce the zinc, instead of receiving a fair 

 price for it a deduction of forty cents per unit of zinc is made for roasting it 

 out of the ores. This and the charges for reducing, amounting to $10 or 

 $15, and $3 per ton railroad freight, reduces the ore value at the near- 

 est smelters to about $20 to $25, which, after deducting the actual cost 

 of mining and interest on capital invested, does not leave sufficient profit 

 for mining enterprises on a small scale. Again, the work done, even in these 

 two mines, is hardly anything but preparatory to mining. Shafting and drift- 

 ing are only the opening of a mine, the actual paying work beginning with 

 stooping. The Hazel mine at the foot of the Sierra Diabolo is both better 

 developed and worked on a larger scale, and fine silver- bearing copper ores 

 in considerable quantities were shipped last spring. From reliable informa- 

 tion it is ascertained that about ten carloads were shipped each week for ten 

 consecutive weeks. The present output is not as high, but is still high 

 enough to yield a good profit. Very little prospecting has oeen done in the 

 Carrizo and Sierra Diabolo Mountains, although $10,000 worth of silver-bear- 

 ing copper ores were taken from one prospect, the Don Quixote and Sancho 

 Panza, from pockets not more than twenty feet below the surface, and the 

 immediate vicinity of these prospects shows a number of equally inviting in- 

 dications and outcrops. Near this locality a well defined lead of black oxide 

 of copper can be plainly traced on the surface for several miles, but with the 

 exception of one shaft, about 50 feet deep, and some very shallow prospect 

 holes, no work has been done on it. 



The Sierra Diablo proper consists on its southern slope and on its eastern 

 edge, for the first eight miles at least, of horizontal strata of the Upper Car- 

 boniferous deposits, resting on a layer some sixty to seventy feet thick of a 

 conglomerate of amygdaloidal pebbles, cemented together by a red arena- 

 ceous silico-calcareous matrix. The pebbles get smaller in the lower strata, 

 and change finally into fine-grained, uniform, red sandstone. In this sand- 

 stone is found the lead of the Hazel mine, a gangue thirty to thirty-five feet 

 wide of strongly siliceous limestone, without distinct walls. The limestone 

 of the gangue, which is ore-bearing in its whole width, contains a pay streak 

 or pay streaks of strongly argentiferous copper ore, mostly copper glanz, of 

 a thickness varying from a few inches to ten and twelve feet. This limestone 

 gangue becomes more arenaceous on each side of the vein, until it assumes 

 the character of the country rock. 



The experience of over 500 years in mining teaches that ore deposits (veins 

 and lodes) are more frequently found in mountainous regions than in level 

 countries; that they are more frequently found in older (plutonic) than in 

 newer, and (perhaps iron excepted) more frequently in the vicinity of eruptive 

 than of sedimentary mountains. That the presence of iron outblows, or 



