358 ANCIENT ABORIGINAL TRADE IN NORTH ASIERICA. 



"was, about ten years ago, among tlie Shasta Indians in California, sa^ 

 one of the tribe engaged in makiug arrowheads from obsidian as well 

 as from the glass of a broken 'porter-bottle. He describes the method 

 of mannfactnre in a letter which was published by the American Eth- 

 nological Society.* To this letter I shall refer in a succeeding section 

 of this essay, when treating of the division of labor among the North 

 American Indians. Mr. Bartlett visited, while in California, a locality 

 in the Napa vallej^ (north of San Francisco), where obsidian occurs 

 in pieces from the size of a pea to that of an ostrich egg, which are 

 imbedded in a mass resembling a coarse. mortar of lime, sand, and 

 gravel. He found the surface in many places covered, from six to 

 twelve inches in depth, with broken pieces and small boulders of this 

 volcanic substance. The appearance of these spots reminded him of a 

 newly-made macadamized road.t 



The most extensive use of obsidian, however, was formerly made in 

 Mexico, before the empire of the Aztecs succumbed to the Spanish in- 

 vaders. Old obsidian mines are still seen on the Cerro de Navajas, or 

 "Hill of Knives," which is situated in a northeasterly direction from 

 the city of Mexico, at some distance from the Indian town Atotouilco el 

 Grande. These mines provided the ancient population of Mexico with 

 vast quantities of the much-i)rized stone, of which they made those fine 

 double-edged knives, arrow and spear-heads, mirrors, very skilfully 

 executed masks, and ornaments of various kinds. Humboldt speaks of 

 the Hill of Knives in a transient manner ;| for a precise description we 

 are indebted to the meritorious English ethnologist, E. B. Tylor, who 

 visited that interesting locality in 185G, while traveling through Mexico 

 in company with the late Mr. Christy.§ In describing the mines, Mr. 

 Tylor says : " Some of the trachytic porphyry which forms the substance 

 of the hills had happened to have cooled, under suitable conditions, from 

 the molten'state into a sort of slag, or volcanic glass, which is the obsid- 

 ian in question ; and, in places, this vitreous lava, from one layer hav- 

 ing flowed over another which was already cool, was regularly stratified. 

 The mines were mere wells, not very deep, with horizontal workings 

 into the obsidian where it was very good and in thick layers. Eouud 

 about were heaps of fragments, hundreds of tons of them ; and it was 

 clear, from the shape of these, that some of the manufacturing was done 

 on the spot. There had been great numbers of pits worked, and it was 

 from these minillas, little mines, as they are called, that we first got an 

 idea how important an element this obsidian was in the old Aztec civi- 

 lization. In excursions made since, we traveled over whole districts in 

 the plains where fragments of these arrows and knives were to be found 



* Bulletin of the American Ethnological Society, New York, IrtGl, Vol. I, p. 39. 



t Person al Narrative, Vol. II, p. 49. 



t Essai politique sur la Nouvelle-Espague, Vol. Ill, p. 122. 



§ Tylor, Auahuac : or Mexico and the Mexicans, Ancient and Modern, Lond., 1861. 

 This volume contains, hesides many facts relating to the archaeology and ethnology of 

 Mexico, the hest observations on obsidian I have found in any work on that country. 



