Paul K. Dickman wrote:

Tom McDonald wrote in message ...

Paul,

I'm getting a good free education in this copper business. I
thank you and Gary for your tutelage.

I don't recall reading anything about, for instance, silver
artifacts in the upper Great Lakes area; but this doesn't mean
it wasn't used. I rather suspect that folks were breaking rocks
to extract copper, and may have discarded as debitage the
non-copper bits.

I'll have to look into this, as it would seem that silver might
have been present in large enough amounts that it might have
wound up in archaeological contexts. And, of course, when white
folks came later to investigate and further exploit some of the
copper deposits, I'd be surprised if any silver were to have
been ignored by them.

Tom McDonald


You're missing my point.
Given that casting pure copper is difficult and produces an inferior
product, the casting of copper, simply to save you time forging, is a fool's
errand.( Any craftsman worth his salt would figure this out by the third
try. )
The only good reasons for doing it, are to make a bigger piece of copper or
to clean the rock out.

Eventually, either of these tasks would lead to noticeable alloying.

I would expect this to show up in a full assay of the artifacts.

I've tried to follow this thread, (well, I wandered off when it turned into
a shouting match) and I've yet to see anything that says that all the
artifacts are 99+% pure copper or , in fact, that any were. I am sure that
some testing must have been done, but I am a metalsmith not an
anthropologist, and the relevant research has eluded me so, I have been
unable to ascertain this one way or the other.

Paul K. Dickman

Paul,

Sorry. I got your point, but went off on my own tangent in my
reply. I have gotten the idea that casting copper of the purity
found in the UP mines and drift copper redeposited by glaciers
is, as you put it, a fool's errand when forging was well known
and widely practiced.

Your question about the purity of the copper in the artifacts
is interesting. For my part, most of my sources tend to take it
as a given that the copper artifacts in the upper Great Lakes
area were nearly pure copper. I know that I've read articles
that nail this down, and I'll try to get hold of some of them.

A kind person posted these links to articles in the Central
States Archaeological Journal. You might find them interesting
as they describe a series of experiments by one Joseph Neubauer,
Sr., designed to see how the copper artifacts observed in the UP
of Michigan could have been made. The first link is to an
article discussing the characteristics of the material he used.
The second is to a general introduction to the Neubauer
experiments, and a step-by-step discussion of his process. The
third is an overview and summary of the Neubauer Process. I'm
not a metalworker, but ISTM that most of the information needed
to replicate this Neubauer Process, and by extension the general
method known to have been used by the ancient Indians of the
area, may be found in these articles.


http://www.csasi.org/2003_summer_jou..._poundings.htm

http://www.csasi.org/2003_spring_jou..._poundings.htm

http://www.csasi.org/2004_january_jo...er_process.htm

In the 1947 book, _Indians Before Columbus_, by Paul S. Martin,
George I. Quimby and Donald Collier, all in the Anthropology
Department of the Chicago Natural History Museum, I found this
on page 42:

"Many pieces of copper obtained from burial mounds and from
aboriginal camp sites have been chemically analyzed, with no
trace of any tempering agent ever reported. In fact, the
analyses prove conclusively that the copper in all the specimens
examined is native copper, such as is obtainable without
smelting at certain places in North America today, and that the
aboriginal inhabitants were ignorant of the process of
recovering copper from copper ores or of tempering or hardening
by alloying copper with other metals."

I'll keep looking, however I have yet to come across any good
evidence that the copper artifacts in the upper Great Lakes
region were made from anything but the ca. 99.75+% pure copper,
with occasional incidental inclusions of very small amounts of
other materials.

Hope that is helpful.

Tom McDonald