FURTHER MINERAL COLLECTING IN MEXICO 



By W. F. FOSHAG 



Curator, Division of Mineralogy, U. S. National Museum 



After leaving Laredo, the border point on the Mexican National 

 Railroad, the traveler proceeds for a short time over flat and uninter- 

 esting country. Soon, however, he sees before him, rising from the 

 monotonous plain, rugged mountains, the first of the series of loosely 

 connected ranges that make up the Sierra Madre Oriental. From here 

 south, mountains are always close at hand, some of them low rolling 

 ridges, but most of them steep or palisaded masses of limestone or 

 flat -topped ridges of broken lava. Scant brown herbage or stretches 

 of scattered thorny scrub, cactus, and yucca cover much of the coun- 

 try : only the highest elevations are forested with groves of pines 

 and cedars. 



When one has passed the first range he enters a mineral region rich 

 in gold, silver, copper, lead, and zinc. There are also minor deposits 

 of mercury, antimony and tin, and of precious stones — topaz, turquois, 

 and opal. Numerous evidences of mining activity can be seen as the 

 train passes southward, but the most important localities are away 

 from the main line and hidden in the heart of 'rugged ranges. 



On this, my third trip into Mexico, it was my desire to seek new 

 collecting fields ; consequently at Monterey, the first important point 

 on the railroad, I stopped for a few days to obtain information from 

 mining men regarding favorable localities to visit. This modern city 

 is almost surrounded by high and rugged mountains, the most striking 

 of which is the Sierra de la Silla, or Saddle Mountain, lying a short 

 distance north of the city. From here I proceeded to the district of 

 Concepcion de Oro to explore its mines of copper, silver, lead, and 

 zinc. The high granite peak of Temerosa, one of the highest points 

 in the state of Zacatecas is the focal point of the district ; to the south 

 lie the copper mines of Aranzazu and Concepcion del Oro; to the 

 west and north the lead, silver, and zinc mines of Bonanza, of which 

 the Providencia is now the most important. Its extensive workings 

 penetrate the mountain for long distances and extend through the flank 

 of the range to connect with mines on the other side. The peak of 

 Temerosa is flanked on all sides by steeply tilted beds of limestone 

 and shale, and it is at or near the contact of the granite with these 

 rocks that the important bodies of ore lie. 



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