Re: Large cities at time of contact Re: diseases and immunity
Tue, 02 Jul 1996 10:40:23 -0700

Philip Deitiker wrote:

> Why do you say this (gee , do i really want to get in this argument).
> The quality of the aztec glass knives was quite superb.

I do not doubt the quality of the craftsmanship. That was not my point.

> From what I here, were quite durable seeing that they were used in great numbers
> of ritual sacrifices. There was an industry in mexico for mining and
> chiping these knives to workable form (meaning division of labor for a
> specific task).

I have personal experience with the manufacture of stone tools, including volcanic
glass, and it is far from durable, as I explained earlier. However, if you want
scientific validation, compare obsidian (the stronger of the vocanic glasses with
70% silca) to flint (with 90% silica).

Are you saying that an entire industry was built around the production of glass
blades? Distinct from the production of flint and jade blades?

> As far as glass knives are concerned, they are still
> being used in the feild of tissue preparation for electron microscopy
> since they produce a much sharper edge and maintain the edge longer
> than metal and I would consider them a 'high tech' thing, than high
> tech production of knife is little different from what aztecs did.
> So although they are less maliable than metal the quality of the edge
> must also be taken into consideration. I might add the quality is no
> different in manufactored glass than in natural glass once one begins
> to chip the glass (except for tempered glass which can't reliable be
> chipped).

I do not see how you could possibly believe this. There is a big difference
between manufactured glass and volcanic glass. For a start, manufactured glass is
missing the impurities inherent in volcanic glass (ie obsidian is only 70% silica
vs 72% just in common soda-lime glass, almost 100% in fused silica glass). The
structure of manufactured glass is more uniform than that found in volcanic glass
(due to the controled processes of manufacturing, ie even cooling. Because of
uneven cooling, obsidain often contains quartz or feldspar crystals which weaken
the structure of the glass).

These are only the most obvious difference.

The modern blades you mention are likely to be a form of fused silica glass. This
is in no way comparable to volcanic glass. The edges of the blade are also likely
to be laser cut. This produces a far more reliable blade than chipping. Basically,
your Comparison of such fused silica blades to chipped volvanic glass is like
comparing surgical steel to cold beaten chalcopyrite (no matter how expertly

> BTW glass is not a stone, it is an amorphous homogenouous
> solid with properties comparable to plastic at very low temperatures.

This is about like comparing birds to ducks. Glass is a term which defines
molecular structure. When it comes down to it, glass constitutes a supercooled
liquid rather than a solid. Stone refers to any concreted earthy or mineral
matter. Glass does qualify as a stone.

But, this is beside the point. Volcanic glass was treated as any other stone. The
processes used for the manufacture of glass tools was the same as the processes
used for the manufacture of silicate tools.

> Of course it wasn't common, but it is representative of their quest
> for more refined technologies. I think you might say it was a pinnacle
> of their technologies, used principally by the top guys.

While I have not seen any Aztec glass blades, I have seen their work with jade and
flint. Their knapping skills here are only comparable to that of the Near Eastern
Mesolithic period. There were several far more advanced technologies. These would
include the development of alloys (including bronze), agricultural (ie terracing,
irrigation, and fertilization), and the domestication of animals.