298 GEMS AND PRECIOUS STONES IN THE
serrations
on obsidian from that country. Describing the mines, he 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 obsidian in
question; and in places, this vitreous lava, from one layer, having
flowed over another which was already cool, it became regularly
stratified. The mines were mere walls, not very deep, with horizontal
workings into the obsidian, where it was very good and in thick layers.
Round about were heaps of fragments, hundreds of tons of them; and it
is 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 little mines—minillas, as they are called—that we first
got an idea how important an element this obsidian was in the old Aztec
civilization. In excursions made since, we traveled over whole
districts in the plains where fragments of these arrows and knives
were to be found literally at every step, mixed with fragments of
pottery, and here and there a little clay idol."
From
the center of the State of Ohio to the country of the Shoshones, as
well as the Rio Gila, and the mines in Mexico, the straight distances
are almost equal, measuring about seventeen hundred English miles;
indeed the Mexican mines are a little nearer to Ohio than the other
districts. It would be idle, therefore, to speculate from which of
these localities the obsidian found in Ohio and Tennessee was derived.
The number of articles of this stone that have been met with east of
the Mississippi is so exceedingly small that its technical
significance hardly deserves any consideration. Two large obsidian
knives, about 18 inches long, found in Mexico and of Mexican origin,
and almost identical in appearance, are marvels for their fine
chipping. They are to be seen, one in the United States National
Museum at Washington (see Illustration), and one in the Tro-cadeVo
Collection in Paris. Lip-ornaments, mirrors, and other objects are to
be found in ihe United States National Museum, in the National Museum
in City of Mexico, the Trocadero Museum at Paris, the Archaeological
Collection of the British Museum, London, and M. Goupil's collection at
Paris. A
