276 
THE GEOLOGIST. 
knives chipped off it lying close by, and fitting accurately into their places 
upon it. 
" Now to make the case complete, 
we ought to find such prisms in 
Mexico ; and accordingly, some 
months ago, when I examined the 
spleudid Mexican collection of Mr. 
IJbde, at Heidelberg, I found one 
or two. No one seemed to have 
suspected their real nature, and 
they had been classed as maces, or 
the handles of some kind of weapon. 
I should say from memory that they 
were seven or eight inches long, 
and as large as one could conve- 
niently grasp ; and one or both of 
them, as if to remove all doubt as 
to what they were, had the strip- 
ping off of ribbons not carried quite 
round them, but leaving an inter- 
mediate strip rough. There is ano- 
ther point about the obsidian knives 
which requires confirmation. One 
can often see on the ends of the 
Scandinavian flint knives the bruise 
made by the blow of the hard stone 
with which they were knocked off. 
I did not think of looking to this 
point when at Mr. Uhde's museum, 
but the only obsidian knife I have 
seen since seems to be thus bruised 
at the end. 
" Once able to break his obsidian straight, the workman has got on a long 
way in his trade, for a large proportion of the articles he has to make are 
formed by planes intersecting one another in various directions. But the 
Mexican knives are generally not pointed, but turned up at the end, as one 
may bend up a druggist's spatula. This peculiar shape is not given to answer 
a purpose, but resiilts from the natural fracture of the stone. 
" Even then, tlie way of making several implements or weapons is not 
entirely clear. We got several obsidian maces or lance-heads — one about ten 
inches long — which were taper from base to point, and covered with taper 
flutings ; and there are other things which present great difficulties. I have 
heard on good authority that somewhere in Peru the Indians still have a way 
of working obsidian by laying a bone wedge on the siirface 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 
Fluted prism of obsi- 
dian ; the core from 
wliicli flakes have 
been struck off. 
Aztec knives or razors. 
Long narrow flakes of 
obsidian, having a sin- 
gle face on one side, and 
three facets on the other. 
