274 



THE GEOLOGIST. 



after, an Englishman who had lived many years at the Real offered to take us 

 out for a day's ride ; and the Company's Administrador lent us two of his own 

 horses, for the poor beasts from Pachuca could hardly have gone so far. The 

 first place we visited was Penas Cargadas, the 'loaded rocks.' Riding through 

 a thick wood of oaks and pines, we came suddenly in view of several sugar- 

 loaf peaks, some three hundred feet high, tapering almost to a point at the 

 top, and each one crowned with a mass of rocks which seem to have been 

 balanced in unstable equilibrium on its point — looking as though the first puff 

 of wind would bring them down. The pillars were of porphyritic conglomerate, 

 which had been disintegrated and worn away by wind and rain ; while the great 

 masses resting on them, probably of solid porphyry, had been less affected by 

 these influences. It was the most curious example of the weathering of rocks 

 that we had ever seen. Prom Penas Cargadas we rode on to the farm of .Gua- 

 jalote, where the Company has forests, and cuts wood and burns charcoal for 

 the mines and the refining works, Don Alejandro, the tenant of the farm, was 

 a Scotchman, and a good fellow. He could not go on with us, for he had 

 invited a party of neighbours to eat up a kid that had been cooked in a hole 

 in the ground, with embers upon it, after Sandwich Island fashion. This is 

 called a barbacoa — a barbecue. We should have liked to be at the feast, but 

 time was short, so we rode on to the top of Mount Jacal, twelve thousand feet 

 above the sea, where there was a view of mountains and valleys, and heat that 

 was positively melting. Thence down to the Cerro de Navajas, the 'hill of 

 knives.' It is on the sides of this hill that obsidian is found in enormous 

 quantities. Before the conquerors introduced the use of iron, these deposits 

 were regularly mined, and this place was the Sheffield of Mexico. 



" We were curious to see all that was to be seen ; for Mr. Christy's excellent 

 collection, already large before our visit, and destined to become much larger, 

 contained numbers of implements and weapons of this very peculiar material. 

 Any one who does not know obsidian may imagine great masses of bottle-glass, 

 such as our orthodox ugly wine-bottles are made of, very hard, very brittle, 

 and — if one breaks it with any ordinary implement — going, as glass does, in 

 every direction but the right one. We saw its resemblance to this port-wine 

 bottle-glass in an odd way at the Ojo de Agua, where the wall of the hacienda 

 was armed at the top, after our English fashion, apparently with bits of old 

 bottles, which turned out to be chips of obsidian. Out of this rather unpro- 

 mising stuff che Mexicans made knives, razors, arrow- and spear-heads, and 

 other things of great beauty. I say nothing of the polished obsidian mirrors 

 and ornaments, nor even of the curious masks of the human face that are to 

 be seen in collections, for these were only laboriously cut and polished with 

 jewellers' sand, to us a common-place process. 



Cortes found the barbers at the great market of Tlatelolco busy shaving the 

 natives with such razors, and he and his men had experience of other uses of 

 the same material in the flights of obsidian-headed arrows which ' darkened the 

 sky,' as they said, and the more deadly wooden maces stuck all over with 

 obsidian points, and of the priests' sacrificial knives too, not long after. These 

 i hings were not cut and polished, but made by chipping or cracking off pieces 

 from a lump. This one can see by the traces of conchoidal fracture which they 

 all show. 



" The art is not wholly understood, for it perished soon after the Conquest, 

 when iron came in; but, as far as the theory is concerned, I think I can give 

 a tolerably satisfactory account of the process of manufacture. In the first 

 place, the workman who makes gun-flints could probably make some of the 

 simpler obsidian implements, which were no doubt chipped off in the same way. 

 The sect ion of a gnu-flint, with its one side flat for sharpness and the other 

 side ribbed for strength, is one of the characteristics of obsidian knives. That 



