36 SMITHSONIAN INSTITUTION 



dense granite, takes one to Concepcion del Oro, the commercial center 

 of the district and the rail head. 



Matehuala in the northern part of the state of San Lnis Potosi is 

 a little town sprawled out in a harren valley, with little to commend it 

 hut the interesting mineral deposits close by- To the west rises a short 

 hut steep range of mountains, the Sierra del Fraile, at the foot of 

 which lies the famous silver mine, Santa Maria de la Paz. The rich 

 silver ores are found as an intricate vein system cutting shale. Many 

 of the mine workings are extremely hot and until these have pro- 

 gressed sufficiently for proper ventilation the miners can work for 

 only one-hour periods. 



West of the Sierra del Fraile lies a long and rugged mountain 

 chain, the Sierra de Catorce, containing the old and once very rich 

 camp of Catorce. Like the Sierra de Concepcion this range is said to 

 have been forested formerly with pines and cedars but the slopes are 

 now almost bare rock with the scantiest herbage that can be imagined. 

 Only the lower slopes are covered with a growth of cactus, yucca, and 

 similar plants. The town itself is one of the most picturesque in 

 Mexico. It occupies a high shoulder overlooking a deep and rugged 

 canyon, here little more than a cleft in the mountain range. Behind 

 the town rise mountain slopes of red, mauve, and purple shales, almost 

 totally devoid of grass or other vegetation. Its population, once num- 

 bering over 50,000, has dwindled to less than 400 persons, but the 

 town, except for its lack of the human element and the usually ubi- 

 quitous dogs and pigs, seems little changed from its original condition. 

 The houses and shops are well preserved, the sloping streets with 

 their paving of geometrically laid cobbles are worn but still intact. 

 Above all rises the huge bulk of the cathedral, built, it is said, at a 

 cost exceeding one million dollars. The mines are scattered over the 

 barren hills about the city and over the ridge toward the more recent 

 town of Potrero. 



The ore-bearing veins occur in both shale and limestone and are 

 variable in width. The smaller ones are often very rich, and some of 

 the larger ones contain great bodies of extremely rich ore — the bonan- 

 zas of the early days of mining — in the leaner vein matter. Like 

 many of the rich old camps of Mexico, the mining works are impos- 

 ing structures. At the San Augustin mine not only workshops but 

 also the mine chapel have been hewn out of the solid rock at the mine 

 entrance. 



From Catorce I proceeded to Charcas, one of the oldest of Spanish 

 towns in Mexico. It lies some distance from the main line of the 



