Copper Casting In Ancient America

I don't think you've identified the controversy, Yuri. The question is whether the Indians worked only native copper (free, metallic copper, akin to native iron, or bog iron) or if they smelted it from ore.
It's well known that they worked native copper. They were doing it when the white man arrived in North America. That's what the town of Yellowknife, NWT is named for.
For that matter, the Indians in several areas, such as here in NJ, also worked bog iron. But it was such a rare thing that they can hardly be said to have leapt into the iron age.

Thanks for your reply, Ed.
Ed Huntress wrote: Well, they could have also smelted native copper, in order to make casts.
Yes.
Could you please provide more details of this?
How rare was it (working bog iron)? Have some iron smelters been identified in your area?
All the best,
Yuri.
Yuri Kuchinsky in Toronto -=O=- It is a far, far better thing to have a firm anchor in nonsense than to put out on the troubled seas of thought -=O=- John K. Galbraith

This is interesting to me because I have on three or four occassions tried to cast copper with little success. The casting is always full of holes. I assumed some gas was taken in in the liquid phase and outgassed as the phase changed back to solid. It would seem that a flux of some sort is needed but I didn't go any further with it. How is copper cast without this problem? Rick

At one time, the American Museum of Natural History in New York has on display some BRONZE artifacts made by native americans (Inka?). Bronze can only be formed by melting the copper and adding the alloying materials.
John Kopf
Yuri Kuch>

. The term "smelt" usually refers to chemically reducing a metal from its ore (although the use is not entirely uniform -- sometimes it just means the same thing as "melt." But in reference to metals and metal ores, it usually means chemically reducing at high temperatures). They could have melted native copper or any metallic copper without much trouble, using wood charcoal and a blast of air to generate the high temperatures required, but whether they smelted it from ore is a question.
I don't know about ancient methods for smelting copper. You probably could find info about it on the web.
Someone in this thread says he had difficulty melting and casting copper; it came out porous. That's the basic problem. It has such an affinity for oxygen that it requires special methods to cast it without gaining porosity.
I'm afraid I don't have any. It's something I remember from state history classes, decades ago. "Mining" bog iron (actually, scrounging for lumps of the stuff) was the earliest real industry in the southern part of New Jersey. The bogs in the NJ Pine Barrens contain one of the largest concentrations of bog iron in N.A. What I recall is that the Indians there had made some objects from it in pre-colonial days. There also was some Indian use of meteoric iron, if I recall correctly. That was done all over the world, before the methods for smelting it became widespread. Of course, meteoric iron is very rare.
Iron is relatively easy to smelt, combining charcoal and iron ore (iron oxide). When you mix the two and heat them up to some temperature above 2200 deg. F or so in an oxygen-lean environment, the carbon produces CO and the CO combines with the iron in iron oxide to form CO2, leaving metallic iron behind. That kind of smelting was discovered thousands of years ago in various parts of the world, such as India. As I said, though, I don' t know what the reaction is for copper ore, nor how they smelted it. Today, it's a chemical-and-electric process.
There is a fair amount of information about it on the web. I didn't check out any sites, but searching Google for Bog Iron Indians produced over 4,000 hits.

The prospectors of the 1840s soon discovered others had preceded them. Along the Keweenaw lie 5,000 ancient mining pits. Clearing these produced stone hammers, wooden pails, and copper tools. Some held copper masses elevated on wooden cribbing that crumbled when exposed to air. Col. Whittlesey of Cleveland estimated 10,000 men working 1,000 years had accomplished this work. Curiously no habitations or burial grounds were found. Yet some race of antiquity had carried away millions of pounds of native copper. This puzzle is one of the great prehistoric mysteries of North America.
Every Keweenawan has a theory who the ancient miners were: Aztecs, Vikings, Phoenicians, Atlanteans, Moon Worshippers, visitors from the Water Planet--you name it. Science dates the ancient mining at 3000 BC to 1000 BC and credits Indians of the Old Copper Culture for the work--all for home consumption. Others point to the European Bronze Age and suggest a trans-Atlantic trade in native copper until iron smelting tanked the market. Finds of hieroglyphs, astro sites, and altars to BAAL are claimed on the Keweenaw. The rational mind smiles, but such tales conjure up a fine mystique when cruising the brooding evergreen cloaked crags. Plus all the copper implements found in Indian mounds added up don't amount to diddly squat when compared to the total copper mined in ancient times. Where did the rest go?
Gunner
That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

Eh, they say the memory is the second thing to go. I'd better clear up something about bog iron.
Bog iron actually is a highly concentrated iron ore. Some sources say that free-iron (native iron) is not found in bog iron. Others say that small lumps of native iron have been found in bog iron deposits. I have seen one lump of native iron about the size of a soccer ball, allegedly found in a bog iron deposit, in a museum years ago.
Most sources say that almost all native iron is actually meteoric iron, except for a few iron-nickel deposits in the US.
Sorry, I don't have time to track it down further. To complicate matters, it appears to be true that some bog iron is so concentrated that it doesn't need much or any reduction to free the metallic iron in it. It can just be melted out, more or less, although those sources don't seem to be very technically astute. Just guessing here, but I'll bet they mixed some charcoal in with the bog iron to generate enough heat, and that also supplied some CO.
Or maybe not. I do recall a story from south Jersey that iron of such purity was found in the 'Barrens that blacksmiths could just heat it in their forges and forge it on an anvil. It would be interesting to track down the stories but it seems to be such a mix of history, technology, and ancient myths that it would take some real work.
Ed Huntress

"Ed Huntress" skrev i meddelandet news:wcCsc.44477$ snipped-for-privacy@news4.srv.hcvlny.cv.net...
That's not all stories. Concrete evidence is presented in [oh no is she going to put her pet-book forward again :-) YES I am] Iron and Man In Pre Historic Sweden. In academic articles such as:
Calissendorff Karin, Linquistic Evidence for Early Iron Production, ur Iron and man in Prehistoric Sweden, and Holmqvist Wilhelm, The first Iron in Sweden, ur Iron and Man in Prehistoric Sweden and Serning Inga, Prehistoric Iron Production, ur Iron and Man i Prehistoric Sweden, and Thålin-Bergman Lena, Blacksmithing in Prehistoric Sweden,ur Iron and man in Prehistoric Sweden,
as well as all the other essays you can find the information thought not to exist from real life analyses and studies.
Inger E

Thanks, Inger. Do those sources say that the ancient Swedes found native iron in bogs? I do recall that the Swedes were *smelting* bog iron ore in very early times, but maybe you know if they had native iron, as well?

"Ed Huntress" skrev i meddelandet news:gKCsc.44627$ snipped-for-privacy@news4.srv.hcvlny.cv.net...
I don't recall that. Have to check my notebooks.
Inger E

I'm not even sure how much smelting was necessary given that the copper on Isle Royale in Michigan was extremely pure.
Duncan Craig

The short answer is it never existed. The article here: is written by the person who is probably the leading authority on the subject. She looks at the questions you raise.
Doug

Doug Weller says in news:m95kpe1v8f1b$.1nylifljbg8da$. snipped-for-privacy@40tude.net:
Thanks Doug, link added.

There is native copper in Michigan's UP, and that doesn't require smelting. However, if you're going to cast it, you still have some problems. I don't know how the ancients solved those, either.
Ed Huntress

Ed,
There isn't much evidence to say that 'the ancients' in the Lake Superior region had any trouble working the pure native copper without melting it or casting it. OTOH, there is what I consider to be convincing evidence that Native Americans of that region were sophisticated in the manufacture of tools and ornaments from copper by working it cold, or by heating it below its melting point.
The ancients almost certainly solved the problem by ignoring it.
Tom McDonald

Ed Huntress wrote in message ... The primary problem with casting pure copper is it's the absorption of oxygen while in the molten state which it releases as it solidifies. But native copper is far from pure, by modern standards. It contains trace amounts of zinc, tin, lead, gold, silver, arsenic, etc. Any number of these can be very effective deoxidizers.
Also, they weren't casting gasket rings for the space shuttle. They were casting preforms and ingots to be hammered out later. Or simple decorative items. In either case, their standards for surface quality and structural integrity were not overly stringent.
Paul K. Dickman

Not according to some authorities, and this is the crux of the controversy. There is some x-ray evidence of casting in the case of some Indian artifacts from the region:
Ed Huntress

Paul,
The native copper we're talking about (from northern Wisconsin/Upper Peninsula of Michigan) is 99+% pure.
Do you have any evidence that pre-Columbian Native Americans in the Lake Superior area did, in fact, melt copper? I haven't seen good evidence for that, and lots of evidence for its being worked either cold, or hot but below its melting point.
Tom McDonald

Ed,
Can you tell us what one should expect to find in the archaeological record if copper casting were to have occurred? The evidence for the use of copper in this area goes back at least several millenia BC (I've heard up to 7,000 ybp), and occurs early on in pre-ceramic contexts.
How familiar are you with the metallurgy of copper, especially in castings? (There was no need to smelt copper from ore in that area.) Also, how familiar are you with the technique of xeroradiography in metallurgy? I don't know enough about it to tell whether the voids shown are really the result of casting, or might have resulted from folding (for the linear voids), etc.?
Tom McDonald