ty, that somewhere in Peru,
the Indians still have a way of working obsidian by laying a bone wedge
on the surface of a piece, and tapping it till the stone cracks. Such a
process may have been used in Mexico.

We may see in museums beautiful little articles made in this
intractable material, such as the mirrors and masks I have mentioned,
and even rings and cups. But, as I have said, these are mere
lapidaries' work.

The situation of the mines was picturesque; grand hills of porphyritic
rock, and pine-forest everywhere. Not far off is the broad track of a
hurricane, which had walked through it for miles, knocking the great
trees down like ninepins, and leaving them to rot there. The vegetation
gave evident proof of a severe climate; and yet the heat and glare of
the sun were more intolerable than we had ever felt it in the region of
sugar-canes and bananas. About here, 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--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. Round 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
civilization. In excursions made since, we travelled over whole
districts in the plains, where fragments of these arrows and knives
were to be found, literally at every step, mixed with morsels of
pottery, and here and there a little clay idol. Among the heaps of
fragments were many that had become weathered on the upper side, and
had a remarkable lustre, like silver. Obsidian is called _bizcli_ by
the Indians, and the silvery sort is known as _bizcli platera_.[11]
They often find bits of it in the fields; and go with great secrecy and
mystery to Mr. Bell, or some other authority in mining matters, and
confide to him their discovery of a silver-mine. They go away angry and
unconvinced when told what their silver really is; and ge