Alright, I have to ask - what the hell is a "comal" (it aint English!)??? I know of a "Comal River" associated with "Guerrero", there is "Comal County", there is a town in Mexico called "Comal"... there is something "El Comal" that appears to refer to "great home-cooking from Michoacan, Guerrero, Jalisco, and Oaxaca, prepared by Luz Herrera Ibarra, a biology teacher from Acapulco."
It appears to be a utensil/cover plate of some type, but ... but.... "The "comal" used during the Epi-classic was made of clay. The modern "comal" is a large round cast iron plate placed over a heat source." Not copper by the look of it and indeed cast!!
You're being confused by Eric's use of an obscure term of art for geochemically processed copper originating in a water saturated subsurface environment. All that "meteoric copper" means in this context is that it was deposited geochemically from a mildly acidic aqueous fluid whose watery origin was surface precipitation (rain->meteorology->meteoric), rather than liberation of water of hydration in the deep rock.
A more complete explanation is that rainwater percolated down through faults in volcanic rock and reacted with volcanic sulphur to form a mild sulfuric acid solution. This acid solution, raised to temperatures on the order of 350C in the basement rock (and still liquid due to the high pressure there), then dissolved copper being held in more complex oxide or sulphide form in the deep rock, producing a solution of CuSO4. Over time, geologic processes forced this copper laden solution back up towards the cooler surface regions. When iron bearing rock was encountered, the reaction
CuSO4 + Fe => FeSO4 + Cu
resulted. Since copper and iron sulphates are soluble in water, they are free to move about in the rock following fissures and faults. But metallic copper isn't soluble in water, so after the reaction it is left behind to form "veins" of native copper in the rock matrix.
To go into excruciating detail on this process requires knowledge of physical chemistry, equilibrium solutions, and a good bit of geology to understand why it works as it does.
For example, I'd expect objections from the lay person that since there is iron in the deep rock too, the geochemical refining process should have redeposited the copper there. But it doesn't, because the high temperature and pressure in the deep rock shifts the equilibrium point of the reaction in an unfavorable direction for that to occur. Higher up, where temperatures and pressures are lower, the reaction can proceed to a more favorable equilibrium with respect to copper precipitation. (There are other factors too, but I'm not going to write a geochemical treatise here.)
In any event, this natural geochemical refining process means that native copper (meteoric copper) consists of veins of extremely pure crystalline copper. This is what makes native copper so desirable, it doesn't have to be smelted or further chemically refined, it merely needs to be mechanically separated from the rock through which the veins pass.
Just as veins in the body come in different sizes, so too do ore veins in a rock matrix. The vein can be hair thin, or several feet in diameter, or any size in between. That means chunks of native copper come in all sizes, allowing the ancient craftsman working at a sufficiently rich site of native copper, such as Keweenaw, to choose the size of raw material appropriate for making whatever artifact he chose.
I heard back from the librarian at the NIST. He says they don't have L-C 444 anymore, but that is because it's missing, not because they don't curate them. (It turns out that L-C 445 is about painting radiators in steam heat systems :-))
He said he would contact other libraries that maintain collections of the old NBS Letter-Circulars. If he gets a copy, he will snail-mail a copy to me; if not, he'll tell me 'no joy'.
Still waiting to hear from New York Testing Labs. They apparently were bought by a larger firm a few years ago, but it looks like they maintained their name. The work they did, at least on the three indicated artifacts, probably was done on contract with the National Museum of Natural History. If so, the Museum might have to consent to releasing the report, if NYTL still has it.
Who did you contact about Mallery's papers? Would it help, do you think, for me to contact them as well?
I never said that the matter was settled. Gary and Paul have lent us expertise I don't have, and as I learn more, I'm trying to apply it correctly to the info I have. I think that soon I'll know enough to at least ask reasonable and germane questions of the literature, and living archaeologists. Them's good fun!
Again, never said any one person would have all the pieces of the puzzle. However, Gary certainly knows more than I did; and Paul is adding more still.
BTW, in another post (to Phil, I think) you said that I seemed to have not seen, or to have ignored, the NYTL and NBS information. I have not ignored it. However, it seemed reasonable to me to actually get and read Mallery's book, and to learn more about the issues involved before going off half-cocked.
Now I'm looking into getting the reports themselves, and/or Mallery's papers regarding the reports (as well as Ellinger's comments). Seemed like the reasonable approach to me.
Gary Coffman says in news: snipped-for-privacy@4ax.com:
Metallic copper is readily oxidized by Oxygen with dissolve clorine under acidic conditions. Forms copper chloride which is soluble in relative high concentrations. Nitrates and other acids that are also present can do similarly. The problem with Sulferic acid, the product of hydration of S03 produced by volcanism is that it is incredibly unstable, and tends to deprotonate protonating anything. This will result in the protonation of NaCl forming NaHSO4 and HCl which is capable of catalyzing the oxidation of metalic copper to copper I chloride. When this is neutralized the copper with precipitate, forming copper carbonates usually.
It is a certain Irony of chemistry that sulfate is an oxidant, but because its so stable it generally doesn't act as an oxidant, but HCL which is technically a reductant can catalyze the oxidation of metals. The reason it can do this is that metals generally form a coat of oxide on the surface that prevent the underlying layers from oxidizing, the chloride ion, In the case of copper, although sulfate can solubilize copper I and II salts, the most common metal that coats copper is calcium or other common divalent cations. This is the reason its not good to have absolutely pure water running through copper, a small amount of calcium coats the copper and protects it. However calcium carbonates and calcium/copper complexes with carbonate are completely stable in acidic chloride solutions, and once the divalent cations are stripped from the surface of the copper it is free to oxidize with oxygen free radicals that are dissolved in water. Thus if the metalic copper is exposed to s acid sulphate solution, with contaminating salts of chlorine, floride or bromine, the consequence will be the oxidation of the metal.
Eric Stevens says in news: snipped-for-privacy@4ax.com:
Eric, Inger logic doesn't work well even when she uses it, why would you think it would work better when you use it. You quoted a source that claimed that copper tool casting was prevelant from south american all the way to north america. That was your qoute. What I was doing was expanding upon the types of tools that the most prevalant copper cultures in the New World had made, aka not cast copper. IOW, I was descrediting your source and your quote, however obvious that was you failed to see it. My opinion is that, fundimentally, you're unfamiliar with mesoamerican culture. [Despite lengthy number of references I have given last year to educate you guys on the primary research on the evolution on New World metallurgy]
That is, again, because you are unfamiliar with meso and south american culture.
And what I demonstrated was that casting was not the primary form of copper tool formation. IOW I am discrediting Mallory's claim by questioning whether casting was used for tools as ubiguitously as believed or was it for more experimental or recreational activities. The tool manufactoring industry in mesoamerica is no secret, what appears to be is the use of casting in that industry.
The claim of Mallery is self-discrediting, who needs to deal with it, Mallery.
Mallery went south. You failed to get the point.
I am by no means an expert on all metallurgy over all of the precolumbian americas (PCA) but I have yet to have seen a form or mold used in PCA to cast any metal object. If copper was routinely cast to form even trinkets, one would expect the molds for such object to be present somewhere. I am sure such molds probably exist somewhere; however I don't think that casting was a common practiced and was probably practiced amoung the elite metalurgist in the larger civilizations.
What I have seen is pretty much what we talked about earlier with iron, in that partially smelted copper was fused by many men with mallets banging slag into comals.
On Sat, 03 Jul 2004 00:38:46 GMT, Martyn Harrison originally top-posted but I have corrected this:
'meteoric copper' is copper precipitated by the action of 'meteoric water'. See
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and
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"After hydrofracturing, temperature gradients and increased permeability along fractures caused meteoric waters to circulate through the pluton, effectively leaching metals from the porphyry and precipitating them in hypogene, hydrothermal veins."
Apart from that, your interpretation of the term 'meteoric' as referring to wacking great lumps of copper from space is understandable but incorrect.
My use of the term is correct. There are all kinds of ways of forming copper deposits of all kinds of purities. The unusually high purity of the Michigan deposits is attributable to the their 'meteoric' origin.
Even if I wasn't, the knowledge has almost nothing to do with NA copper.
A question by you is sufficient to discredit something?
Gee! You must be important!
It might look that way but only because you (again) snipped some of my text without indicating the fact. Some people regard this as a dishonest practice.
It vanished with a past computer crash. I originally wrote to the Smithsonian and they then referred me to a person at the (?) National archives (?). I contacted that person who referred me to another who never gave me a meaningful response no matter how I (gently) pressed them. I think a fresh start is a very good idea.
Yup, I agree. I guess I have to, since your crash leaves us bereft of stale starts :-).
I'd appreciate any thoughts you have on contacting folks about this. Wasn't there some small museum that might have received Mallery's papers after his death?
I figured that. You don't suppose I'd let that pitch hang up there if I thought you actually *meant* it as written, do you? :-).
I already said it was brazing. I couldn't think of the specific decoration name before, but it is used in making "mokume gane" as found, and originating on samurai sword handles from about 1600 ->
1800.
Are you suggesting silver "sweats" (forms liquid beads) way below its melting point?
If you had not been so intent on being snaky you would know that "aqueous" (correct spelling) also means "water like", "watery" as well as "of or containing water" - therefor it is NOT a clear explanatory term in itself. Further to that, you would NOT have written that formula up there - but if you want to argue that particular formula (A) point out how two solids, suddenly for no given reason, decides to react and change (B) how they get together in the first place when they are NOT ambulatory in any way. Oh and where are these pure iron deposits, hmmm? It sure as hell would have saved on building blast furnaces if that existed...
You could have instead pointed to this section in that same article: "Into the lava flows of Keweenaw, Houghton, and Ontonagon counties percolating hot waters rising from great depths brought copper and silver in solution. As it cooled, the waters filled the fissures and the gas cavities (amygdules) of the lavas (trap rocks) with pure copper and silver..."
Now here we see something totally different from your "formula". There IS a mention of a "solution" - most likely the copper portion was CuSO4.5H2O. There is not a single mention of iron. It also refers to a heat source - not two ambulatory minerals meeting in the dark for a bit of kissy kissy, saliva swapping or any other hanky-panky!
So what have we here - we have the result of hot lava, the water "evaporates" leaving what would be known as, Blue copper, Blue stone or Blue vitriol (among other things) or CuSO4. Indeed it does exist, but it isn't your pure Cu, is it.
BUT if I again go back to your "formula" and introduce some "Fe" into the equation, it has to be as "FeSO4.H2O" solution - 100% water soluble (used in animal feeds as a supplement). Perhaps more interesting is the FeSO4.7H2O (copperas), also water soluble, but is blue in colour similar to copper sulphate and in its solid form it melts at 64 deg. C! Only problem is that this requires no hanky-panky at all.... the Fe is pregnant with SO4 already!
So lets add the bit of "mood" to the situation and heat it up with the cooling lava. The result would indeed be ferrous and cupric oxides, respectively, giving off water and sulphur trioxide, which combine to produce a dilute solution of sulphuric acid.
So IF there is either some "copperas" or Ferrous Sulphate Monohydrate in the CuSO4.5H2O - then one can expect IRON to be present with the copper - well.... yes but not in the same place by the look of it. But then if we take both the copper and Iron out of the soup we end up with H2SO4.... or masses of sulphuric acid (oil of vitriol)! Therefor Lake Superior is a lake of acid. Then the Moral of the Story is: don't eat the fish as they will eat your insides out!
Now, I have to admit I have have happily forgotten 99% of what I ever learned about chemistry (except that needed to make moonshine), but then again, why on earth am I required to know any of it.....?? To prevent you getting all snooty by suggesting things??
Anything can be welded at virtually any temperature by using pressure. The Mini Minor crown wheel for the diff started off as a steel disc cut off from a round billet. This was placed on a mould at the end of a hydraulic ram, and the other half of the mould was on another hydraulic ram. To form the crown wheel they were slammed together under huge pressure - it made a very nice crown wheel - and fast!
The evidence of porosity is available to the naked eye in that thin copper flake. There are dozens of tiny bubbles in evidence, You don't even need a radiograph to see them. A radiograph or a density test would settle the matter absolutely, but neither is really needed here as the sizes and numbers of bubbles already visible are clear indications of atmospheric melting.
The large numbers of tiny pits in that piece are suggestive of porosity, but a stereo radiograph, or a density measurement, would be required to determine if the piece is actually riddled with porosity, or if we're just seeing corrosion pitting of otherwise sound copper (if the object is indeed copper, and not a bronze alloy).
Pre-Columbian, or Spanish Conquest? I don't see a precise dating associated with the individual objects. The web site says the collection of objects date from the Post Classic and Spanish colonial periods. Also, the web site says the objects are a mix of copper, copper-tin bronze, and copper-arsenic bronze. What evidence do you have that the two particular objects you selected from that collection are pure copper rather than bronze?
You're wrong on both counts. Copper is a malleable, ie plastic, material even at room temperature. At annealing temperature (500F or greater) it is much more so. Bubble gum need not be molten for bubbles to be formed in it, neither does copper. And while copper can be welded, in an inert atmosphere, by melting, it can also be welded at lower temperature by pressure.
And wind up with a porous lump of no use to anyone. Really, you haven't absorbed anything anyone has been telling you about the atmospheric casting of pure copper.
That's your interpretation. But since your interpretation is wrong, your conclusion is also wrong.
Actually, I can make the claim, because heavily alloyed copper is no longer native copper.
It is a conclusive indication for any case where silver inclusions are found.
Neither Tom or I have conceded R666 was cast. We've agreed it shows all the characteristic signs of atmospheric melting, but it doesn't automatically follow that it was deliberately cast.
Copper does not need to be heated to melting for blisters to form. Please go back and reread Neubauer for examples of native copper which blistered on annealing *without* being raised to melting temperature. You can blow bubbles in bubble gum without melting it, you can do the same in copper. It merely has to reach a sufficient state of plasticity for the gas pressure from inclusions to deform it into a blister.
illustrates the basic mechanism. The same kind of thing happens with copper and silver. The presence of silver will lower the melting point of the copper and a solid solution will be formed. In the case of copper and silver
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the lowest melting temperature as 779.583 plus-minus 0.060 which is lower than the melting point of either copper or silver.
Many metals will form similar eutectic mixtures with copper, particularly aluminium and zinc. Some tin-lead solders will form eutectic mixtures with high alloy steels at quite low temperatures, which is why at an early stage they stopped soldering identifying labels onto aircraft undercarriage legs. :-)
I suggest you read the opening paragraphs of
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don't take this as a contradiction. I intend it as an elucidation. :-)
"A huge copper boulder on the Ontonagon River, said by Alexander Henry (the first white man to describe it) to weigh five tons led, in 1770, to the first copper mining venture in the UP. This first mining venture started near the boulder that lay 20 miles from the mouth of the Ontonagon River. The "Ontonagon Boulder" was eventually shipped to the Smithsonian Museum and now resides by the Mall Entrance to the Museum of Natural History. Michigan has been trying to get our Boulder back, but the negotiations are a bit slow. You know what happens when things go to Washington. It is about the size of a VW Bug and weighs about 5 tons. "
Other large "mass copper" pieces have been found on the surface in the UP. One article I came across while googling said that some of the large masses show evidence that ancient peoples had made attempts to flake pieces off of them (tool marks).
Here's another example of "mass copper" http://64.90.169.191/education/history/images/copboy4.gif And here:
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