copper yes, bronze yes, silver yes(to pour in forms) but not iron. That they
didn't do until they began trading silver, furs and eagles with the Norse
according to the oral tradition I have had from respected Indians I spoken
I agree that is most likely to have been the procedure. On the other
hand what we don't really know is if the porosity was a problem for
I suspect you are using modern ideas as a guide, knowing of other
techniques etc. Back then in learning about melting copper, they must
observe it melt. Learning annealing they again need to observe the
effects, thereby also learning to heat to just below melting point and
lend itself to the "hammer welding" you refer to below.
....and it would also eliminate porosity, would it not? So the small
bit could well be melted and cast into a small ingot - to later
"hammer weld" the porosity out of it.
I'm aware of the difficulty - as well as the evidence it provides of
casting. As such evidence does exist, even if not widely, it indicates
the ability to melt copper.
Try the old 3 cent piece - it was silver + copper alloy. Nor does it
need to be "fit for casting" in the modern sense, as all I see it used
for is to generate a larger lump of material to work with as a smith
A copper alloy is in general called "bronze" irrespective of the mix
(eg arsenic + copper) except when it is called "brass" (nickle +
No, it has been done a lot of the time. In Sweden (damn I lost the
info tag..) they have something they call "malm" (ore) that is a
bronze, but a far redder colour than normal bronze. I can't tell you
the mix of it as I lost the info. However there is a lot of arsenic +
copper bronze around in Asia Minor. It was mined in the Ural mountains
as a ready mixed ore.
It does if you heat it to the melting point of copper.
Tin is indeed the most common, but not the sole mix.
It is still called "bronze" as the "bronze age" term itself says.
Ahhh.... but irrespective of the fact that artisans may get their nose
out of joint, melting/smelting metals IS called a "technology". So
having that technology under ones belt in addition to the smithing, is
indeed one up on the smithing alone :-)
Not suggesting modern people do cast copper - I am saying ancient
While there is/was almost pure copper available at the time, much of
it had impurities embedded within it. Large hunks of pure copper were
relatively rare. The vast amounts that are indicated to have been
mined must include copper with much impurities or copper embedded in
other material. This had to be refined somehow, melting is the
simplest way of refining it - unless you know of another technique
available to the ancients.
Nobody is suggesting that smithing isn't an extremely skilled
occupation..... but then so is flint knapping in my view. The casting
was not used to manufacture anything much apparently. I see it as a
refining process to later be hammered at near melting temperatures,
thereby producing fine artefacts.
As I said mastering one technology, is less than mastering TWO
technologies.... if you want to call smithing a "technology" in favour
of Art :-)
I don't know what if any testing of composition of artefacts has been
done. Some bronzes only contain 3 -> 5% tin elsewhere. If none are
done then a claim that bronze doesn't exist can't be made. Testing the
metals would also finger print them for origin, which hasn't been done
either to my knowledge.
SIR - Philosopher unauthorised
Considering copper :
1. find some rich ore or native or near native.
2. build one hot fire - continue burning and increase coal / charcoal contents.
3. add copper or ore - perhaps using glass technology of the time - pit glass ?
more melted stone that is glassy and use this slab as a cookie sheet . :-)
4. cover the top with more fuel and then cap it off - perhaps air vent on the
side of the wind...
A reduction fire - and when cooled off it might have metal in the sheet...
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer firstname.lastname@example.org
No, it couldn't. Porosity isn't just little bubbles in the metal. Those
bubbles contain air, and at molten temperatures, the oxygen in that
air would oxidize the inside of the bubble. So what you wind up with is
a mass of copper with a lot of oxidized holes in it. You can't weld
copper that is oxidized. If this happens when a modern TIG welder
is welding copper (gas shield failure), the only thing he can do is
grind out all the porosity and start over.
No trick to melting copper. Doing something intelligent with the molten
metal in an atmospheric environment is a different matter. As I noted
previously, casting pure copper is difficult, even today. For a people
without inert gas shielded continuous casting furnaces, it would be
nothing but frustration.
But the question is, how pure was the copper.
In any case, copper can mostly by prevented from oxidising by melting
it under a layer of crushed coal or charcoal. In fact this method was
used for the production of largely deoxised (tough-pitch) copper in
Don't under rate the cunning of anceint man.
The native copper we've been discussing is very high purity.
The halfbreed ore does contain silver, but the silver isn't in
solid solution with the copper (copper-silver alloys are difficult
to produce). Instead it is in the form of distinct crystal inclusions
which would melt out and separate before the copper would melt.
A graphite cover was used to prevent oxidation while melting (coal
won't work because of the large fraction of volatiles, charcoal might
be useable). But you also have to deal with the air entrained when
A bottom pour furnace is helpful, but you really need deoxidizers in
the alloy to prevent severe porosity problems. Tin and zinc are the
preferred deoxidizers. Arsenic also works, but the fumes are deadly.
Lead makes the metal more fluid, and assists in filling out the mold.
None of those are naturally present in the native copper we're
Also, as a side note, where is the evidence for coal mining or large
scale charcoal production in the area? You don't get to copper
melting temperatures with a simple wood fire. You need a forced
draft fire with a high carbon fuel.
Don't underestimate the difficulty of getting sound pure copper
castings. Low alloy bronzes and brasses (approx 0.5% to 1% tin
or zinc respectively) aren't too bad to cast, high alloy bronzes
and brasses are easy. But casting pure copper is hard, even
with today's technology.
Again, porosity is the problem, and that should show up on
radiographs, as it does for R666 (which certainly shows evidence
of being melted in atmosphere, though not necessarily evidence
of being cast), but none of the other artifacts presented show
that sort of porosity.
I believe we are agreed that only atmospheric casting was within
reach of the ancient Native Americans (or ancient Old World
founders for that matter), so we *should* see characteristic
porosity in any pure copper items they attempted to cast. Now
of course the Old Worlders had the advantage of ores which
did contain suitable deoxidizers. They weren't actually casting
pure copper. But the Michigan copper was essentially pure
Here is a quote from 'Metallurgy for Engineers' Rollason, 2nd Edition,
first published 1939:
Production of Tough Pitch Copper. In fire-refining copper the
impurities are removed by oxidising the metal until about 4 per cent
copper oxide (Cu20) is absorbed. During this stage the impurities form
oxides more readily than the copper and are removed as a slag or
evolved as gas. The last impurity so removed is sulphur which is not
completely driven off as sulphur dioxide by mere oxidation, but to
remove the last traces the metal has to be violently agitated by
poling, i.e. introducing an unseasoned piece of wood under the
surface. This causes a miniature fountain of molten copper, and allows
the air to come into contact with the spraying metal. Small test
castings or button castings are taken to indicate the state of the
metal. With sulphur present the ingot spurts just as it goes solid due
to the evolution of gas (SO2), but as the sulphur is reduced in amount
the surface of the ingot sinks in the manner normal to most metals. If
a micro-examination is made of this metal it will be found to contain
globules of copper oxide in the form of a eutectic (Cu-Cu2O). A layer
of crushed coal is then placed on the molten copper, and as poling
continues the copper oxide is reduced and when a content of about 0.04
to 0.08 per cent oxygen is reached the surface of the button remains
level and the properties of the metal are good, in other words
"tough." The lower the oxygen, the higher the so-called "pitch" and
vice versa, hence the name "Tough Pitch." As poling continues past
this point the copper absorbs hydrogen from the furnace gases and when
cast the metal rises on solidification.
These changes in behaviour, micro-structure and mechanical properties
are due to the influence of hydrogen and oxygen on the copper.
The above confirms not only the use of crushed coal but also the
primitive nature of the processes by means of which relatively pure
copper was produced even in the 20th century. Stirring with a piece of
unseasoned wood is a practice which may have roots going back for
My point is that our ancestors have had a habit of producing materials
with primitive techniques which we have now largely forgotten about.
The fact the we now do things only with modern gizmos doen't mean that
our ancestors couldn't do much the same thing some other way.
A good bed of well ventilated charcoal will suffice. One often finds
melted copper in the remains of burned out buildings.
Once again, it depends what you mean by pure. Somewhere I have seen
reference to a recognised ancient copper alloy containing 0.5% As
which was produced by addition of the As. Clearly they were able to
produce copper with less than that level of As.
Only if they used the relatively pure meteoric copper of Michigan. It
was laikely to be naturally alloyed if it was smelted.
But it wasn't the only source of copper.
This thread began, and has mostly developed, around that
Michigan (with some from Wisconsin and Minnesota) native copper,
more specifically its use in the upper Great Lakes area.
Yuri has begun a thread about copper casting outside of this
area. Perhaps that would be a better venue for this more
general discussion of ancient copper.
The quote is a procedure for smelting chalcopyrite ore. That's a very
different procedure from what is required to process pure native copper.
Apples and oranges.
A fully engulfed large building, or a forest fire, can produce sufficient
natural draft to reach copper melting temperature, but you'd need a
forced draft for a simple bed of charcoal. For doing very small amounts
of metal, such as small silver jewelry items, blowpipes would suffice, but
for doing anything on the order of the size of the artifacts we've been
examining, a bellows or blower would be required, and a *lot* of charcoal.
Let me propose that you conduct an experiment. Go to your local "high
end" audio shop and purchase some oxygen free copper "monster" wire
(similar properties to native copper). Now try to melt it in your backyard
barbeque. The insulation will burn off, but I'll be very surprised if you can
get the wire to melt without a forced air draft and *several* loads of
Making charcoal is an industrial enterprise in itself. I'm asking is there
any evidence of such activity in the area under discussion? So far I
have seen no reference to such activities. Nor have I seen any reference
to coal mining activity in the area. All that has been reported is mining
of native copper deposits.
Meteoric copper? Perhaps you're thinking of iron. The copper we're
discussing is native copper. Native copper is the result of a natural
geochemical leaching process in certain types of rock formations.
It results in extremely high purity copper.
True, there are impure ores present in the region as well. But
there is absolutely no evidence that any of it was mined or
processed prior to the latter part of the 19th century. Further,
the impure ores which are present contain iron and sulphur
as their major contaminants. Those impurities are extremely
undesireable in copper that is to be cast. The ore has to be
smelted to remove those impurities.
No significant amounts of tin, zinc, arsenic, or lead, which
would improve casting qualities, are present in the ores of
the region. So even if the ancients had adulterated their
native copper with these ores, the result would not be an
improvement in the ability to cast objects from the resultant
The ancients lacked a scientific understanding of metallurgy,
but they weren't stupid. They proceded by a sequence of trial
and error steps. If they added something, and the result was
worse, they'd quickly understand not to do that again. Since
the Native Americans in Michigan already had access to very
high purity native copper, and any local adulterant they added
would only make its properties worse, I'd suggest that they
quickly learned not to add any adulterants.
Now the situation was different in the Old World. The metalworkers
there had access to adulterants which *would* improve the casting
properties of copper, and they fairly quickly learned to add such
materials to their copper. That's not because they were brighter,
it is simply because they had materials at hand which weren't
available to the ancients of Michigan.
I don't know where you get that from. The opening sentence says very
clearly "In fire-refining copper ... ".
But then that's not why I quoted the article. I did so to deal with
your rebuttal of the use of a layer of coal to prevent oxidisation.
Actually I have carried out that very experiment to replicate damage
seen to 'Monster cable' in a domestic fire. Just for the heck of it I
through some into the base of a Jotul Alpha wood stove. The monster
cable variously melted or sintered into a solid bar of copper. FYI,
the Jotul Alpha is an 'air-tight' stove with the only air entry being
down the face of the front door glass from the top.
That's a very different question from the use of coal to prevent
Its a term used to describe the copper deposited by contact with
meteoric water. Meteoric water is ground water formed by
Those pictures do not show any evidence of the characteristic
porosity copper casting would produce. The single large surface
bubble is a blister, common when the surface of a wrought piece
is overheated. Compare it to the radiograph of R666. The latter
does show the characteristic deep pattern of porosity of an at least
partially melted copper object.
But the imperfections due to casting pure copper *would* produce the
characteristic porosity which is *not* seen in any of the pieces other
than R666. As I have remarked in other posts, it is possible that this
single sample may have been melted due to a cause other than
deliberate casting, so by itself it is not conclusive evidence for a
copper casting technology, though it is suggestive.
In any event, none of the other objects show the porosity signature
of atmospheric casting. So even if the ancient people found flawed
castings acceptable (and such castings would be weak and brittle),
the lack of porosity is strong evidence that none of these particular
items, with the possible exception of R666, were cast.
Not everything that is possible is probable.
Wishing won't make it so.
Yuri Kuchinsky -=O=- http://www.trends.ca/~yuku
A great many people think they are thinking when they are
merely rearranging their prejudices -=O=- William James
They disagree with you as it states "The casting bubble can clearly
In my experience of examples of all kinds - no two are ever identical.
Again, I point to the fact they disagree.
One cant make that claim without investigation, there hasn't been any
undertaking by others do examine artefacts for casting. Again I point
to the article:
Neiburger said "Further xeroradiographic surveys and analysis of the
25,000 existing copper artifacts from that period (Archic Midwestern
United States) are necessary for the determination of how extensively
early Native Americans had used melted metal."
It doesn't look like any real studies has been done to say casting was
NOT practised - or that it was. Personally I don't expect a hell of a
lot of casting due to the pure copper being available (even if not
always in large lumps) - but I cannot dismiss the evidence, limited as
it is, considering the LACK of research undertaken so far.
SIR - Philosopher unauthorised
Gary showed that the porosity typical of pure cast copper is
not present in that artifact. He even explained in just below.
Do you know what 'characteristic' means in this application?
It appears 'they' were mistaken.
Yes, there has. Please note that every artifact that does not
show the internal characteristics of melted copper is evidence
against that item being cast. And, as Gary and Paul have
pointed out, when an artifact shows clear evidence of having
been made by smithing, that is evidence against it having been
Again I point
I fully agree, and hope that more such studies are done.
We've been looking at the evidence for a bit now, on this
thread. The evidence for casting that's been presented so far
appears to have suffered in the course of examination. That
said, I would very much like to see more investigation done on
Seppo, would you care to comment on this last by Gary?
Please point out the "porosity" in this sample:
Two copper pigs:
The casting is obvious in this:
Both pictures show melted copper - pre Colombian melted copper! It
leaves Gary's statements hanging in the air.
However if one considers that "bubbling" has been claimed to be caused
by "overheating" in a annealing process - then it is saying "melted"
at the same time, as it cannot bubble UNLESS a portion of it is
melted. Also "welding" requires the melting of the metal - or so
goddamned close to it that the friction heat generated by a blow on it
does melt the metal.
Those are two logical examples of melting occurring - the knowledge of
melting copper existed. It beggars belief that scraps and off cuts
were NOT melted when the process must have been known to them. That
people suggest they would rather go and do hard manual labour another
day to find a piece "just right" for the job, when it is right there,
right now, right before them. All they have to do is melt it into one
The implied suggestion they would rather do the hard labour, and not
proceed with the easier option available immediately to them, isn't
consistent with known human behaviour.
SIR - Philosopher unauthorised
The one who is educated from the wrong books is not educated, he is
First, the porosity would be most likely visible on
radiographs, or in a section through the bubbles. You haven't
given me the information necessary to determine this for these
Second, no one argues that no copper was ever melted in
pre-Columbian North America. The question, especially for the
upper Great Lakes area, is whether this was done by humans; and
if so, whether it was done on purpose to make tools or ornaments.
Third, the artifacts shown are from Lamanai, Belize, and
date from after about 1200 AD. They have el zippo to do with
copper work in the Upper Great Lakes area in the Archaic. Is
that why you posted links to the photos, but not to the web page
they're on? That page specifies all this:
"Copper and bronze (copper-tin and copper-arsenic) began to
arrive at Lamanai during the 13th century AD. Provenience
studies conducted by Dr. Dorothy Hosler at the Massachusetts
Institute of Technology revealed that the copper used to produce
many of these items was obtained from West Mexican ore fields."
This is grasping at straws, Seppo.
Woulda coulda shoulda. As Inger what value to place on
The implied suggestion is that the Indians wisely used the
techniques that produced the best tools and ornaments for them.
As Gary has pointed out, often, and you seem not to have
grasped, casting pure copper is very inferior to forging pure
copper in terms of the quality of the finished product.
Choosing to use a process that produces a lower quality result
over a well-known process that produces a higher quality result
is not consistent with known human behavior.
Indeed. The fact of "bubbles" doesn't necessarily point to of
"overheating" while annealing. That radiographs are needed to
determine casting means it cannot be determined from a visual
inspection unless a un-worked piece eg like the small pigs in the
picture. This work hasn't been done for the artefacts that I can find
- therefor I cannot give it - nor can you then claim "not cast" for
You certainly could have fooled me. I has seen a number of instances
where it is claimed no s/melting was needed the copper was worked by
hammering. That embeds the statement "no s/melting".
I highly recommend you withdraw that and rephrase it - lest you want
to be seen saying "native people are not humans"!!
The web site URL is posted in another message. The pictures were the
relevant part for this issue of "obvious porosity". Again you are
wanting to look at the label, ignoring the content!
I just take the opportunity to remind you that West Mexico is in
What "straws"? Is the above right or wrong? Where is your common
sense? Note the picture again where I point to casting is obvious -
that picture suggests a considerable overheating of the metal to have
that result. This simple fact points to problems with temperature
control - it would be no different when annealing something -
temperature can (and is so claimed) get too high so the material
melts. Them not noting this is suggesting people are (A) blind (B)
stupid. I say they were aware of the method required to melt copper.
Why do you disagree considering your earlier statement "no one argues
that no copper was ever melted" - but yet you do exactly that right
None of the above applies at all Tom - you are operating with a closed
mind at present, and doing your damnedest to contradict your claim "no
one argues that no copper was ever melted"!!
You would further argue that they elect doing something that is much
harder in favour of something that is easier. This is unrealistic. It
is a very modern notion to make bikes that go absolutely nowhere, even
when pedalled for hours!
I suggest you look at Paul's message, and follow the links therein:
Again, as it almost always is, there is more to this than meets the
eye - the simple claim "casting makes poorer quality - therefor it
wasn't done" is far, far too simplistic.
SIR - Philosopher unauthorised
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