# Talk:Copper/Archive 2

Perhaps someone with more time can add a section about the discoverd link between copper and Alzheimers. (to those who have some resistence to this, most things can be harmful if there is a vulnerability or excess of...e.g. water)

• Research as recent as 2007, conducted by Dr R. Squitti, Head of the Laboratory of Biology of AFaR and of the Laboratory of Neurobiology in the University "Campus Biomedico" added, "'Free' copper may be intrinsically toxic to older persons due to its oxidative activity, small size and ability to cross the blood brain barrier and enter the central nervous system in an unregulated fashion, similar to elevated 'free' copper's effects in other diseases of copper metabolism, such as Wilson's disease." [1]

Thanks

--Caesar J.B. Squitti: Son of Maryann Rosso and Arthur Natale Squitti (talk) 17:11, 20 September 2008 (UTC)

More guesses. [1] [2] [3]
Bork (talk) 14:17, 21 September 2008 (UTC)

## No Table of Chemical Information

This article is missing a table of chemical information. Other elements have table in the topic right that shows a periodic table and lists the properties of the element. Could someone please repost the table? Students like me rely on it, thank you! 128.253.197.28 (talk) 02:19, 4 November 2008 (UTC)

Done. Some vandal decided to blow it away. Wizard191 (talk) 02:35, 4 November 2008 (UTC)

## Electron configuration

I know that although the expected config is [Ar]4s23d9, but that from experiments it is shown the have a config of [Ar]4s13d10

Is the reason for this anomaly still disputed amongst chemists or is there a consensus that it is due to the "lower energy of the high spin configuration"?

It seems to me that copper and chromium are notable because of these exceptions, and I was thinking that maybe some more detail about possible explanations for the exceptions could be included in the article

just a suggestion...-Aspiring chemist (talk) 22:01, 16 November 2008 (UTC)

Information for group 11:

Copper: [Ar]4s13d10

Silver: [Kr]5s14d10

Gold: [Xe]6s14f145d10

Roentgenium: [Rn]7s15f146d10

Hmmm... maybe that should be on Group 11 element

--121.7.203.206 (talk) 07:44, 21 May 2009 (UTC)

The electron configuration in the sidebox needs to be changed from 3d104s1 to 4s13d10. Doing this now. — Preceding unsigned comment added by Osteveliam (talkcontribs) 15:55, 3 April 2011 (UTC)

Um, Rg is probably [Rn]7s25f146d9, actually. Lanthanum-138 (talk) 09:58, 1 May 2011 (UTC)

## Mining Map

The map showing the mines in Australia is wrong. They are in the west of Australia and there are more of them.

Please read the caption to the map. See my longer comment under uranium.. Turgan Talk 18:02, 4 December 2008 (UTC)

## Skin/Bio-electrical field reactions with copper jewelry?

I'm just wondering why a copper chain bracelet I made from copper wire, stays shiny as long as I wear it. Of note, I can't wear watches, as my body electricity screws them up. 99.246.242.251 (talk) 18:06, 19 December 2008 (UTC)

For that matter, it would be nice if someone could address the copper jewelry fad of a couple of decades ago (?), as well as the health claims that used to be made for the wearing of copper jewelry, the bluish stain that some people experienced on their skin, and any debunking (if any) of medical claims. 99.136.199.199 (talk) 17:34, 20 June 2010 (UTC)

I don't turn blue/green from copper, I shine the copper by holding it. Natural electrolysis or alchemic reaction? —Preceding unsigned comment added by 156.34.179.53 (talk) 17:48, 23 August 2010 (UTC)

## Colombus

Some one has added that Christopher Columbus had copper sheathing on his ships. This is added on the basis of a statement on a website "copper.info". I do not know enough to be able to say for certain that this is wrong, but I had always understood that until the late 18th century, ships were sheathed with wood: lead had been tried in Britain but was found unsatisfactory. If Colombus sheathed his ships with copper, why did this become part of the regualr shipbuilding technology until nearly 300 years later? The article copper sheathing accords with what I had believed. This is based on a book by Brian Lavery, who is a leading expert on early modern shipbuilding technology. His work should cettainly be the most reliable source, after original archives (which WP does not like having cited). Comments, please. Peterkingiron (talk) 15:08, 1 February 2009 (UTC)

There seem to be quite a number of websites stating this factoid. None of them are really RS but this one is interesting as it has a ref to National Geographic in its bibliography. I do not have access, but here is the ref for anyone that does;
• Scofield, John "Christopher Columbus: The Sailor Who Gave Us the New World", National Geographic Magazine, Vol.148, No. 5 November 1975.
SpinningSpark 16:00, 1 February 2009 (UTC)
I do not have access to it, but the artile is quoted as saying that Columbus' last voyage fell victim to the worm, which implies that they did not have copper sheathing. The article is dealing with an ethnic story of a copper canoe in Canada. I think the author was out of his depth in dealing with copper sheathing of ships. He speculates on the Vikings wishing to have it, but adduces no direct evidence that they did. Peterkingiron (talk) 16:50, 1 February 2009 (UTC)

## Mechanical Properties

I added a jargon tag to the Mechanical properties section of the article because of the use of confusing jargon in the first paragraph. For instance, what is 'necking'? This term could be explained better. The first sentence does not make any sense at all; i.e. talking about a single crystal and then mentioning multiple small crystals. I'm not sure enough about this specifics of this subject to do much of an edit. I'm sure when it was written that it meant something to someone, however it does not communicate well. Does someone with a little more expertise in the mechanics of copper want to try a rewrite? Cuprum17 (talk) 16:55, 23 February 2009 (UTC)

I've done some wikilinking and added some referenced text on the polycrystal stuff. It still needs some work, besides anything else I think the article in now contradicting itself because - I think some of the original text is wrong, or at least confused. "Necking" is now wikilinked, but this, and also even the poly/monocrystal stuff really belong in a "strength of materials" article because it is not specific to copper. More than that, the section is purportedly "mechanical properties" but does not actually state them. This site has all the information on mechanical properties, but I do not have time to extract it and put it in the article right now - I have to go and do some real work. Too many different grades of copper to extract it and make sense in five minutes. SpinningSpark 14:49, 5 March 2009 (UTC)

## ultra dispersed copper scam

I got in contact with this scam by someone who is falling for it. I don't understand how the scam works. Maybe someone here knows. It could be good to create a section about this scam saying that there is no such thing as extremely expensive "ultra dispersed copper" (whatever that is supposed to mean) and that it is a scam. Since millions of people now have the habit of turning to wiki when wondering "what is ...?", that could save potential victims. —Preceding unsigned comment added by 213.159.118.174 (talk) 15:48, 27 March 2009 (UTC)

## Reserves Left

Various estimates of existing copper reserves available for mining vary from 25 years to 60 years, but minute amounts of the mineral can be located in; the earths crust at 50 p.p.m.In soils at 20 p.p.m. Located in the sea water at 0.2 p.p.b. Also found in human flesh at 2-10 p.p.m.(Highest levels in the liver) and human bone up to 25 p.p.m. The only problem is extracting it from any of these locations cost effectively/economically viable. [2] John Emsleys book entitled 'Nature's Building Blocks: an A-Z guide to the elements' — Preceding unsigned comment added by Roberts397 (talkcontribs) 21:37, 26 March 2012 (UTC)

## toxicity

It looks like every article with the word "copper" in it has had this link added - which amounts to spam. It would be better to link to copper toxicity. I've removed a few.— Preceding unsigned comment added by 213.249.232.187 (talkcontribs) 20:37, 3 April 2009

## Corinthina Bronze

Ids ther eany one who knows enough to confirm whether League of Corinth is the correct disambiguation for "Corinthian Bronze"? My impression was that the term referred to a particular allow, rather than specifically to a place of origin. However, even if it is that, I would have expected the link to be to the city of Corinth, rathger than an alliance. Nevertheless, I do not recall that the Bible says more than that the gates of the temple were of bronze. I would suggest that we need an article explianing the term "Corinthian bronze" and an authority for the fact that the gates were of that material, as the identification of the alloy is itself a matter of interpretation. I believe I heard a lecture on "Corinthinan Bronze" by some one from the lesading archaeometallurgist from British Museum a decade and more ago, but I cannot even think of his name, let alone being able to look for an article by him. Peterkingiron (talk) 22:30, 25 April 2009 (UTC)

As we actually have an article for Corinthian bronze I would say that League of Corinth is not the best link, however it is an improvement on the link to the corinthian dab page which is where it used to go. I suspect the editor who did this found that League of Corinth is the only "ancient history" article listed on the dab page and so used that as the nearest match. SpinningSpark 16:58, 1 May 2009 (UTC)

## Shouldn't Copper be in Category:Biology and pharmacology of chemical elements ?

Shouldn't Copper be in Category:Biology and pharmacology of chemical elements ? Eldin raigmore (talk) 20:37, 16 May 2009 (UTC)

## Image in lede section

I have just reverted the editor (Wizard191) who moved the etched copper image into the alloys subsection. This is a nice picture for the lede inserted by another editor, Alchemist-hp, but unfortunately messed the layout a little. To fix the layout, I put the image in as a left-aligned image, since the infobox is already occupying the right-aligned position. Wizard191 moved it citing MOS:IMAGE. I presume he is referring to Start an article with a right-aligned lead image or infobox. It does not exactly forbid left-aligned images and this seems like a reasonable exception even if it were so. In any case, an image of pure copper is quite inappropriate for the alloys sub-section. SpinningSpark 12:48, 10 June 2009 (UTC)

While not explicitly prohibited, do you think the article would pass an FA-review with it there? I don't think it would. Wizard191 (talk) 14:51, 10 June 2009 (UTC)
I don't know whether it would or not, but in my opinion, our aim should be to improve the article, not to rigidly comply with arbitrary rules. If a rule prevents you from improving or maintaining Wikipedia, ignore it is written into policy and should trump the MoS in any review. Anyway, my main objection to your edit was not to insist that the image is kept in the lede (although imo it is an excellent image for that position), my objection is rather that where you placed it is entirely inappropriate - the image is of pure copper and you placed it in the alloys section. If there is a good reason for not having a left-justified image in the lede, then fine, put it somewhere else. SpinningSpark 17:22, 10 June 2009 (UTC)
I have to say I agree with Spinningspark about the image; I think the current location is the best place for the image as no other section in the article really fits, and it does not at all detract from the lead. The Seeker 4 Talk 17:30, 10 June 2009 (UTC)
If you guys think it's alright there, I'm not going to push the point. While I may not have moved it to the best of places, I feel that a left justified image is "off-putting". This is the first article I've been to that has one, so it feels out of place. Wizard191 (talk) 18:42, 10 June 2009 (UTC)
How about moving it down a para or two but keeping it in the lede? Would that cure the feeling of unease you get when looking at it? SpinningSpark 22:04, 10 June 2009 (UTC)
This may be a general question for WP: PROJECT ELEMENT but what's the problem with having photos of all elements in their leads/ledes? Except for colorless gasses, where the image is funny even in the element-box. The problem here is that we created these elementboxes and they tookover and are now making us write articles other than the way we'd like to. I'd like a nice photo of the subject up front in any article about a physical THING or PERSON and elements are no exception. The element box photo is often perfectly usable, but too small. It would be a much more attractive wiki for most elements if there was a 150 px one. And (again) since the element-box-of-the-damned is in our way again, that's why people are putting the photo as left-thumbed. Once again, the box is dictating. Why don't we just say: element boxes are fine, but they don't rule? They're not the boss of us? :) SBHarris 22:43, 10 June 2009 (UTC)
Well you've answered your own question, you need to take it to WikiProject Elements, or even higher, have a pop at infoboxes in general at WP:VPP. You may even get some support, not everybody likes them. I recently saw a poor semi-newbie being chased off a bunch of Featured Articles for trying to put in infoboxes on ones that didn't have them. Personally, I think you'd be wasting your time, the're too ingrained in the community now. In any case, I don't think we have a problem with this particular article. The infobox picture is poor quality and would not be suitable for enlargement and the good one we now have in the lede is not suitable for the infobox picture as that is supposed to be the general appearance of the element. Basically it is good as it is now. SpinningSpark 23:24, 10 June 2009 (UTC)

<-- outdent. Okay, I'll copy this section over there, as all the general issues need addressing. Infoboxitis is something that (IMHO) can be dealt with inclusively, by adding infoboxes but making sure they don't replace other good stuff, and they don't end up dictating everything else. They're meant to help, not be fashion-nazis. In this case, where they tend to inhibit addition of a nice photo in the LEAD, they hinder the project. And for the record, I think it's a crying shame that Pussy Galore has been forced into a "James Bond franchise character" infobox. What's this encyclopedia coming to? It's some kind of obscessional madness. SBHarris 23:33, 10 June 2009 (UTC)

Well as I say, in this particular case the infobox is not causing a restriction. The whole problem was caused by trying to strictly apply the rule Thou shalt open the lede with a right-aligned image or infobox. which is a different issue. Nowhere does it say that should be the only picture in the lede, in fact Wikipedia:Layout#Images talks about not having too many in the lede which kind of implies that more than one are expected. SpinningSpark 00:02, 11 June 2009 (UTC)
Ah. Well the layout of this article now is quite nice in my opinion at least, and if it's not against some policy, I'm going to try to add a few aesthetic pics of other elements to the thumb-left of some chem element articles, as we've done here.SBHarris 00:44, 11 June 2009 (UTC)

## Copper Age and Old Copper Complex

The last sentence under the Copper Age section is very misleading because it follows dates for several cultures having verified copper-smelting technology. The "Old Copper Complex" in the Great Lakes region has possible dates that predate any of the others, and it gives the erroneous impression that the Archaic culture of the Great Lakes Native North American Indians had copper smelting before anyone else! There are NO copper smelting artifacts in the Old Copper Complex- they found and used native copper, they did NOT smelt it. There has never been found ANY evidence for actual copper smelting anywhere in North America. - StevoDog21 (talk) 01:03, 11 July 2009 (UTC)

Some of the dates for the invention of copper smelting around the world look odd, especially West Africa 900-1000 AD seems very late for any part of Africa. "There is evidence that gold and iron were the only metals used by humans before copper" the citation does not provide any evidence, I suggest replacing it with 'Copper was probably the third metal used by humans, after gold and meteoric iron' using the same citation.-Orangutanlibrarian (talk) 17:23, 25 November 2011 (UTC)

I agree this date seems strangely recent, but that is what the source says. It appears to be a geology lecturer's essay, but not about his subject. I am thus doubtful whehrter this is really WP:RS. It is not my area of expertise either. Peterkingiron (talk) 16:34, 26 November 2011 (UTC)

## Peak copper

Production is expected by some analysts to reach a peak at some point in the future and decline thereafter, according to the Hubbert peak theory.

That sentence is almost devoid of meaning. Am I really to believe that there are some analysts who do not believe that a decline follows a peak. Of course there will be a peak at some point, but when? Tomorrow, 10 years, 10,000 years? The sentence badly needs a citation - or deleting. By the way, there is an article on peak copper which shoul probably be linked there. SpinningSpark 06:37, 17 August 2009 (UTC)

## Copper plating

I don't particularly have anything to say on this right now. I just thought we ought to open a discussion on the talk page instead of flaming each other in edit summaries. SpinningSpark 02:17, 4 October 2009 (UTC)

Yes. My thinking behind my reverts was: it is just a single sentence, referenced, introducing a link to electroplating (a process relevant to copper) and logically extending the previous history info on plating. Why on earth deleting it, without providing a reasonable edit summary? Materialscientist (talk) 02:25, 4 October 2009 (UTC)
While I know that copper can be electroplated, but there's nothing in the sentence that explains how it relates to copper for the un-informed reader. I think that the sentence can be salvaged into something informative, but as it currently stands it doesn't flow at all in the history section or explain how it is relevant. Wizard191 (talk) 19:07, 4 October 2009 (UTC)
My reading of the claim is that the plant was the first modern copper-plating plant (rather than electroplating in general) but was unable to verify this as the source is not available online (but the title is about copper). If the statement checks out, perhaps it would go with the later paragraph about the first company to do flash smelting. SpinningSpark 15:41, 8 October 2009 (UTC)

## (post moved from top of page)

PLEASE USE BCE!! Not BC. —Preceding unsigned comment added by 82.181.23.73 (talk) 18:03, 16 October 2009 (UTC)

See WP:ERA, BC is ok by Wikipeida guidelines. SpinningSpark 20:10, 16 October 2009 (UTC)

## Suggest edit

The ease with which it can be drawn into wire makes it useful for electrical work in addition to its excellent electrical properties.

Would read better as: The ease with which it can be drawn into wire in addition to its excellent electrical properties makes it useful for electrical work.

Can't edit because article is protected. —Preceding unsigned comment added by 38.97.4.4 (talk) 17:22, 26 January 2010 (UTC)

I am not sure if this is the correct place to put this. But in the main article on Copper it is stated, under the oxidation states, that one compound that has copper III in it is YBa(2)Cu(3)O(x). This is not really true. From neutron diffraction an modeling I think it is accepted that the copper is in the Cu ++ state and the two of oxygen is in the O- state, not the Copper in Cu+++ state and the oxygen in the O-- state.

I can provide references but they are from about 1993 and before. Does anyone have a more up to date reference on the oxidation state of the copper and oxygen in YBCO? —Preceding unsigned comment added by 128.156.10.80 (talk) 18:47, 28 October 2010 (UTC)

## Nucleosynthesis

This article needs a section on the origin of copper [4]. 188.192.118.79 (talk) 18:49, 12 February 2010 (UTC)

Hi, I don't know how this works on a closed page, but I would like to have the link to my site updated. Note 5 refers to http://elements.vanderkrogt.net/elem/cu.html, this is changed and has to be http://elements.vanderkrogt.net/element.php?sym=Cu the page is the same, but I had to change the urls because of the new database structure. Thanks in advance. Peter 83.84.134.0 (talk) 17:41, 25 February 2010 (UTC)

Updated. Please extend the use of reliable sources on your pages; wikipedia policies toughen in this regard, and web pages which don't comply with this might gradually be removed from references and external links, especially in WP:FA or WP:GA articles, which most elements pages eventually will become. Materialscientist (talk) 23:31, 25 February 2010 (UTC)

## Production

Hi all,

Brand new here and do hope I'm doing this correctly...

The statement,

"Copper is a finite resource, but, unlike oil, it is not destroyed and therefore can be recycled."

Seems a bit inacurate to me.

Oil is recycled when we oxidize it. And I'm pretty sure, nothing is ever really destroyed, just rearranged. On that same note, finite is a bit misleading as well. http://en.wikipedia.org/wiki/Finite

I do understand the author's intent, and on the whole, it is a relatively correct statement.

There may be some subjectivity in it's content.

Regards, Darrell —Preceding unsigned comment added by Itcouldbeme2 (talkcontribs) 01:49, 17 March 2010 (UTC)

I tweaked the questioned sentence as it indeed sounded dubious. Materialscientist (talk) 01:55, 17 March 2010 (UTC)

It also should be mentioned if the US should bother with making the US penny anymore with the cost of inflation it cost taxpayers to make the penny as inflation makes it worth nothing to use it anymore http://coins.about.com/od/uscoins/i/penny_debate.htm —Preceding unsigned comment added by 24.205.229.251 (talk) 22:55, 18 March 2010 (UTC)

## Unclear sentence in "Biological role" section

I added Template:Clarify at the end of the sentence that states: "Food rich in copper should be eaten away from any milk or egg proteins as they block absorption." From that sentence, it is unclear (to me, at least) what blocks what. It could be taken to mean that foods rich in copper block absorption of protein in milk/eggs or that protein in milk/eggs blocks absorption of copper. Could someone clarify this, please? I'm not familiar with the subject matter to do it myself. Big Bird (talkcontribs) 15:50, 20 April 2010 (UTC)

## Incorrect description of color phenomenon

Hello. The article states that the color occurs because of copper's unique band structure. However, the color is maintained in the liquid state. This is inconsistent. Band structure theory relies on an initial assumption of a periodic, repeating lattice framework of the atom cores (usually the materials solid state crystal structure) to make evaluations of the properties. A liquid cannot have a band structure, as the term is used today.

Perhaps its more appropriate to say it relies on the electronic configuration?

Thanks,

--Anonymous

As I understand it, bands are caused when energy level splitting occurs, which in turn is caused by the proximity of atoms to each other. Splitting is still going to occur in a liquid, it does not require periodic spacing to happen, although it might not make for such a neat easy calculation. SpinningSpark 20:26, 25 April 2010 (UTC)
Yes, splitting of the energy levels is retained after melting. There is no traditional E(k) band diagram anymore because momentum k is not conserved, but this doesn't matter so much for color. Besides, in case of metals like copper, the primary cause of color is not the energy levels splitting but the specific configuration of the valence electrons (plasmon is a key word here). Those are not just conduction electrons, but a "combination" of all top electronic levels, and they are weakly affected by melting - experiment shows that plasmon energy is almost unaffected by melting. Materialscientist (talk) 22:52, 25 April 2010 (UTC)
(Author of the original comment) The fact that plasmons are unaffected upon melting is almost a given, since plasmons, as I was taught, come about because of the mobility of electrons within the material and their ability to respond to an electric field (independent of the crystal structure). The conductivity of copper should not be effected much by the melt, and if this is where the color comes from it makes sense. Thank you for your reply. And yes, while energy level splitting will still occur in a liquid, I still have to argue that it won't have STRUCTURE (except on extremely short time scales). The mobility of the atoms in the liquid would tend to average out all of the effects of band structure as atoms move around and away from each other.
Article still said 'band structure' so on basis of above I changed it to 'electronic config' and 'shells'. Hope that's OK. Rod57 (talk) 01:48, 10 March 2011 (UTC)

## Semiconductive properties of copper oxide

There should be few word about Copper-copper oxide rectifier and solar cell and a link to the article "Metal rectifier" too. —Preceding unsigned comment added by 89.133.196.210 (talk) 15:44, 11 June 2010 (UTC)

Do you have those few words ready? If so, either post them here, or leave a note on my talk page asking for the article protection to be removed so you can edit yourself. SpinningSpark 17:06, 11 June 2010 (UTC)

## Source of Confusion .. Units

The specific Heat Capacity has units J/kg/K not J/mole/K -- The latter is the molar heat capacity —Preceding unsigned comment added by 62.49.227.202 (talk) 16:28, 1 September 2010 (UTC)

## ATOMIC WEIGHT

It would be really groovy to include somewhere in the article the fact that Cu has an atomic weight of 63.546. That would certainly be more useful to most of us than the atomic number. —Preceding unsigned comment added by 67.148.9.178 (talk) 20:47, 12 January 2011 (UTC)

See box to the right in the article. Materialscientist (talk) 22:21, 12 January 2011 (UTC)

## Hardness

The infobox says Brinell hardness 874 MPa but that seems far too high. Is there a source for it ? Rod57 (talk) 02:31, 12 February 2011 (UTC)

## New article on copper oxides

Hi. I was wondering if it would be good to start a new article to list all the copper oxides like in the case of Iron oxides, or (better) to list all the known salts of copper.188.230.132.58 (talk) 20:50, 21 April 2011 (UTC)

## Edit request from 86.135.241.193, 25 April 2011

{{edit semi-protected}}

In the section on 'Production' and subsection 'Method' the following equation is incorrect:

Cu2S + O2 → 2 Cu + SO2

The oxidation of Cu2S in this process gives copper(I) oxide. So the equation should be:

2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2

I couldn't help noticing the error being a chemistry teacher !

Tim Bergin

timothius_b@yahoo.com

86.135.241.193 (talk) 11:10, 25 April 2011 (UTC)

Corrected. Thank you. Materialscientist (talk) 11:14, 25 April 2011 (UTC)

## GA Review

Reviewer: Lanthanum-138 (talk) 06:56, 1 May 2011 (UTC)

Since Freywa's been reviewing quite a few of the elements articles (some nominated by me), I'll try doing it the other way round this time! ^_^ Lanthanum-138 (talk) 06:56, 1 May 2011 (UTC)

All right, time for my first GA review. Lanthanum-138 (talk) 07:00, 1 May 2011 (UTC)

GA review (see here for criteria)
1. It is reasonably well written.
a (prose): b (MoS for lead, layout, word choice, fiction, and lists):
2. It is factually accurate and verifiable.
a (references): b (citations to reliable sources): c (OR):
There are a few paragraphs and small chunks of text that still don't have references. I'd be only too happy to pass this once that's over with.
Specifically, Physical (bit about nines) and Methods (entire last two paragraphs). Lanthanum-138 (talk) 07:05, 1 May 2011 (UTC)
3. It is broad in its coverage.
a (major aspects): b (focused):
4. It follows the neutral point of view policy.
Fair representation without bias:
5. It is stable.
No edit wars, etc.:
6. It is illustrated by images, where possible and appropriate.
a (images are tagged and non-free images have fair use rationales): b (appropriate use with suitable captions):
7. Overall:
Pass/Fail:

Nothing's been done yet... Lanthanum-138 (talk) 08:35, 1 May 2011 (UTC)

"The purity of copper in electronics is expressed in nines, with a digit specifying the number of nines in the percentage of purity, followed by an N. The higher the digit, the purer the copper is." Um, we just need something showing this use of nines...
"The cuprous oxide is converted to blister copper upon heating: 2 Cu2O → 4 Cu + O2. This step exploits the relatively easy reduction of copper oxides to copper metal. Natural gas is blown across the blister to remove most of the remaining oxygen and electrorefining is performed on the resulting material to produce pure copper: Cu2+ + 2 e– → Cu." Cool, but got a source for this?
Once these two are this one is cleared, no problems. Lanthanum-138 (talk) 08:56, 1 May 2011 (UTC)
This fact simply does not belong here, I guess. It can be removed. 09:35, 1 May 2011 (UTC)
One down, one to go. Lanthanum-138 (talk) 09:23, 1 May 2011 (UTC)
All done! Entire GA passed. Lanthanum-138 (talk) 09:54, 1 May 2011 (UTC)
The great majority of copper is used for electronics for its conductivity and its maleability. The article deserves explanation (by an editor schooled in condensed matter physics/materials) on why copper functions so well in this dominant application. The article is long on "what" and short on "why".--Smokefoot (talk) 13:23, 1 May 2011 (UTC)
I don't know why this must be any further explained. Copper have greater conductivity than most metals(not including gold, siver and platinum) and it is in price range to be used in this aplications. Does this answer you? 188.230.132.58 (talk) 20:59, 2 May 2011 (UTC)
It seems to be there already. Lanthanum-138 (talk) 13:54, 1 May 2011 (UTC)
"This [conductivity, I guess] is due to all valence electrons taking part in conduction, which results in a charge density of 13.6×109 C/m3 and a drift velocity of ⅓ mm/s at a current density of 5×106 A/m2.[7]" If special to copper (unclear), why do "all valence electrons" in copper "take part" (awkward).... results in a "charge density of 13.6×109 C/m3" (number is non-benchmarked, sounds impressively complicated but its just a number). Similarly the ductility/maleability: "one s-orbital electron on top of a filled electron shell, which forms metallic bonds[1] and have high ductility" (awkwardly phrasing aside), why does this set up give copper high ductility? Maybe my questions are not answerable in an understandable manner.--Smokefoot (talk) 14:23, 1 May 2011 (UTC)

## production part

The methods section in the "production" part could be named: "Extractive metallurgy of copper", and it could also be divided into two parts, which are the two basic metallurgical methods being used globally for the production of copper: 1-Pyrometallurgy of copper(Mainly copper sulfide ores) 2-Hydrometallurgy of copper (Based on copper oxide ores, electro-hydrometallurgy of copper containing electrolysis of the solution). The existing is correct, but is just the first method. I also suggest to have a third section after these two for the refining of copper for electrical purposes. (See Nickel extraction and purification) —Preceding unsigned comment added by Burgundy111 (talkcontribs) 01:10, 8 May 2011 (UTC)

## Is "tarnish" correct in the opening paragraph?

Wikipedia's article on tarnish says it forms on copper (and other metals) but doesn't say it always exists on those metals. If freshly cut copper wire, for example, doesn't develop a tarnish for some length of time, I think the sentence is inaccurate. I might suggest "color" or "hue," or, if the point of the sentence is to introduce the idea of tarnish, changing the verb to "develops." — Preceding unsigned comment added by 50.53.107.77 (talk) 06:44, 20 June 2011 (UTC)

"an exposed surface has a reddish-orange tarnish" should be changed to "an exposed surface gets a reddish-brown tarnish of ${\displaystyle Cu_{2}O}$" Thanks if an expert could verify and made this correction. — Preceding unsigned comment added by 129.70.15.23 (talk) 11:13, 7 July 2011 (UTC)

## Occurrence

Text and specific Ref[16] on stellar synthesis of copper are out-of-place here. I suggest this be deleted. If anything, a link to article on nucleosynthesis could be inserted. Gierszep (talk) 01:45, 24 September 2011 (UTC)

## Copper is semi precious - spam link ?

Copper is semi-precious with a reference to emerilware dot com ? Looks silly and spammy - 180.181.252.167 (talk) 21:26, 18 November 2011 (UTC)

Removed as pure spam. Missed that so-called ref. If anyone wishes to re-add the "semi-precious" bit ... feel free but with a valid ref please. Thanks to the ip for pointing that out. Vsmith (talk) 22:42, 18 November 2011 (UTC)
The term 'semi-precious' in relation to copper seems to appear most frequently in media reports of copper thefts from electricity sub-stations, building sites, etc., due to the current high price of the metal as scrap. I'm not sure that I've seen it used in financial reporting of copper as an industrial commodity. Perhaps a suitable reference can be found in a manual of silver or copper smithing. Use of the term is certainly justified historically due to the metal's use in bronze artworks. Cheers, Bahudhara (talk) 03:02, 19 November 2011 (UTC)
A quick search on Google Books set for 19th century yields only two or three hits for "copper" and "semi-precious metal," somewhat more for 20th century, but not many. It seems to be an ill-defined neologism. The term "precious metal" is genuine, as is "semi-precious stone" (e.g., amethyst), but "semi-precious metal" seems dubious. Zyxwv99 (talk) 15:32, 23 December 2011 (UTC)

## Something is not right with the information about magnetism

At the time of this writing, the entry indicates that copper is diamagnetic. Lots of google results agree. However lots of google results also disagree, stating that elemental copper is paramagnetic on account of its unpaired 4s1 electron. Common experience suggests that copper is not magnetic, but pure copper coins (i.e. not American pennies) in the vicinity of an NMR magnet become magnetic, suggesting that copper is indeed paramagnetic.

If copper is diamagnetic, I'd like to know why it is not paramagnetic as its electronic configuration would lead us to expect.
If copper is paramagnetic, I'd like to know why there is so much misinformation circulating, including the current page.
Verytas (talk) 01:46, 18 December 2011 (UTC)

@Verytas: isolated Cu atoms are paramagnetic. Copper metal is diamagnetic - this is why contradiction in the literature. What happens to small clusters (a few atoms) - I don't know. Since 1857, American penny is not pure copper. NMR magnet is a strong magnet, with a strong field gradient at the edges, and can probably move coins no matter they are dia, para or ferromagnetic. Even minor magnetic impurities will play a role: US dollars are affected by moderate magnetic fields (1 tesla is enough as I recall) because their dye contains some paramagnetic iron salt. Materialscientist (talk) 09:18, 18 December 2011 (UTC)
Why Cu metal is diamagnetic. The 4s1 electrons are delocalized over the whole metal; many have spins up and many down, the sum of those giving zero magnetic moment. Their net spin is not zero though, and this gives a paramagnetic contribution. However, there is also a strong diamagnetic contribution from the paired 4s1 electrons, and, especially, from the completed atomic shells (like 3d10). The math is such that the total behavior is diamagnetic. Materialscientist (talk) 03:37, 19 December 2011 (UTC)
Metallic copper is paramagnetic due to being 3d10 4s1 --an electron electron configuration for Cu(0) that all agree on. [5]. The element box on this page is wrong, and I'll change it. SBHarris 01:57, 18 December 2011 (UTC)
A brief answer, copper and silver are diamagnetic [6][7] (negative permittivity). I'll get back on why - got to run, don't remember by heart, perhaps because of the filled d-shell lying higher than the s shell. Note that electron configuration is for a singe atom, not metal. Materialscientist (talk) 02:05, 18 December 2011 (UTC)
The crux is the difference between atoms and metals. Isolated Cu atoms are odd-electron and thus automatically paramagnetic (S = 1/2). My impression is that bulk Cu, like most bulk metals, is diamagnetic. Famous exceptions in the transiition metals being Fe, Co, and Ni, maybe Mn. --Smokefoot (talk) 02:14, 18 December 2011 (UTC)
Okay. Fix this with qualifications if you can. I'm off on vacation and won't be able to. Feel free to revert my last changes to element boxes for Cu, Ag, and Au. SBHarris 02:20, 18 December 2011 (UTC)

Here is what I figured out while swimming. Magnetism of elements is a quantum phenomenon with no classical explanation. All electrons contribute to magnetism, whereas only the outer ones contribute to conductivity and visible-light optics (color, plasmons), i.e., what matters for magnetism is the whole shell configuration, not the number of "unpaired electrons" - summing up spins neglects the diamagnetic contribution of filled shells, which is not always weak.

Examples: oxygen is strongly paramagnetic, contrary to other chalcogens and common sense (its S=1 state is lower in energy than S=0 state). Al is paramagnetic, while other group-3 elements are not. Pt is paramagnetic and Au is diamagnetic. Be, Zn, Cd and Hg are diamagnetic while Mg, Ca, Sr and Ba are paramagnetic. The 3d and 4d shells (especially 3d) give a strong contribution to magnetism. When they are filled (diamagnetic contribution; Ag to Te, Au to Bi) the corresponding elements are mostly diamagnetic, and vice versa (Sc to Ni, Y to Pd, lanthanides). Materialscientist (talk) 04:40, 18 December 2011 (UTC)

Kinda. In molecular compounds, one does simply total the electrons to distinguish S = 0 vs S = 1/2 because diamagnetic moments are orders of magnitude smaller than paramagnetic moments. The moment of a single electron totally swamps the counter effects of the many other paired electrons. We use Pascal's constants to correct for this difference. Second correction: O2 is strongly paramagnetic (triplet), but so are all the other dichalcogens, as described in disulfur. The other chalcogens tend to form rings without such small π-π* gaps. Now for bulk metals, the situation becomes more complicated, I think because of the effect of conduction electrons requiring more sophisticated quantum mechanics.
(i) All stable oxygen forms (gas, liquid, solid) are paramagnetic, whereas disulfur is not a stable form. Stable forms of sulfur, Se and Te are diamagnetic (though not bimolecular). Most S=0 states have paramagnetic excited states, but they are higher in energy, unlike oxygen. (ii) Electron delocalization is crucial for the strength of paramagnetic contribution in solids (see here), and this makes a big difference between metals and molecules. However, there are a few more effects for which I have no immediate explanation; for example, boron is diamagnetic, yet it is a group-3 semiconductor with a significant band gap. Materialscientist (talk) 07:41, 18 December 2011 (UTC)
Oh, I forgot: bonding in solids is another variable, which discards some predictions from electronic configuration in free atoms. Say, bonding in boron is rather complex (lattice is built by icosahedra, to which normal valence doesn't apply). Materialscientist (talk) 08:04, 18 December 2011 (UTC)
S2, Se2, Te2 are all quite stable (in the way that chemists define stability, i.e. they suffer no unimolecular decomposition). True, at high concentrations, these otherwise quite happy diatomics rapidly polymerize. But that detail aside, these diatomics are all triplets. Just semantics to some, but not a sulfur chemist!--Smokefoot (talk) 08:10, 18 December 2011 (UTC)

Thanks, everyone, but I'm not a whole lot clearer on the issue after this discussion. @Materialscientist - I am particularly confused by some of your statements.

I know that American pennies are not pure copper, which is why I included that as a caveat in my original post. However, I have observed strong magnetic attraction (paramagnetism) between pure copper coins in a region near an NMR magnetic where there was no discernable effect on an American penny. So, not all coins exhibit this phenomenon, as you have suggested. Yet, the H of P&C link you provided clearly indicates that copper is weakly diamagnetic. If that is true, why do pure copper pennies (i.e. not American pennies) attract each other in the field of an NMR magnetic?
Who are you arguing with when your post at 4:40 UTC states that you don't sum the spins, and then your post at 7:41 UTC starting with "Kinda ..." says that you do sum the spins?

Is it possible that single isolated atoms of copper are indeed paramagnetic, but the unpaired electrons that make isolated copper atoms paramagnetic are delocalized in bulk copper metal and pair with the delocalized electrons from other atoms to yield a diamagnetic substance?

If so, then I would expect this delocalized pairing may be overcome in the presence of a strong external magnetic field, or at low temperatures, to yield a bulk metal that exhibits paramagnetism (the weak paramagnetism of bulk copper metal should become stronger as the temp is lowered).
Verytas (talk) 04:30, 19 December 2011 (UTC)

Well we got distracted arguing about our definitions within our hobby. Chemists like to talk about molecules and atoms, but these species have little relation to the properties of bulk metal. We just do not have the right kind of editors here to convincingly explain an answer to your seemingly simple question. However, I have never heard of problems with people having change in their pockets when they work around high field magnets, credit cards yes, but not ordinary US, European, or Australian coins. Also I think that the circuitry in the NMR probes is copper based.--Smokefoot (talk) 05:10, 19 December 2011 (UTC)

(ec) Sorry for confusion - we slipped into a general discussion of magnetism in elemental solids. To your last questions.

Summing spins: spins sum up (by specific rules) in individual atoms. They also sum up for localized electrons in solids. They might not sum up for delocalized electrons in solids (like 4s1 in copper) - because they form an "electron liquid", with its own rules.

Pairing. There is no pairing of 4s1 electrons in copper metal (such pairing only exists in a superconducing state). The effect is more subtle. First, consider individual Cu atoms. Some will have net spin up, some down. Application of magnetic field up will favor one orientation, but temperature will ruin that, and cooling will promote paramagnetism. This is a normal paramagnetic situation - every spin sits on its level and can tumble up and down upon perturbation. In a solid, spins up and spins down form a band of levels, a "half-filled box", where only the uppermost spins can tumble. Others can't tumble because they are packed tight (not in real space, but in energy space, i.e. tumbling requires extra energy to bring the spin to the top of the box where they can tumble). Thus only a fraction of atomic 4s1 electrons contributes to paramagnetism in Cu metal.

Can't answer on coins because it all depends on their exact content and on the experiment. All magnets have regions of field gradient, and this is where you see maximum effect. Further, field, or its gradient will act on any dia-, para- or ferromagnet, just with different strength and sign. Usual assumption is that diamagnetism is weak and thus not noticeable, but it all depends on the magnetic field strength (see here). Materialscientist (talk) 05:17, 19 December 2011 (UTC)

## The alchemy symbol for Copper

Copper's alchemy symbol also is the same symbol as the symbol for the female gender/sex. Maybe you could add that in? Potter76 (talk) 23:54, 30 January 2012 (UTC)

## Origins of word copper?

I'm just a bit concerned that on this page it has the origin of the word copper as; The metal and its alloys have been used for thousands of years. In the Roman era, copper was principally mined on Cyprus, hence the origin of the name of the metal as сyprium (metal of Cyprus), later shortened to сuprum. whereas on the page for native copper it says; The name copper comes from the Greek kyprios, of Cyprus, the location of copper mines since pre-historic times Which is wrong? Or am I just missing something? — Preceding unsigned comment added by BadgerLord (talkcontribs) 01:46, 18 February 2012 (UTC)

The OED3 (online version) says English. The Romans got it from the inhabitants of Cyprus, who spoke Greek. Zyxwv99 (talk) 15:37, 18 February 2012 (UTC)

## Absurd claim of "barely sufficient" resource abundance in the Production section

In the Production section, the articles says: "the quantity available is barely sufficient to allow all countries to reach developed world levels of usage.[18]"

That is an absurd claim, given the 1.365 quadrillion tonnes of copper in-place in the 1.365e20 tonne lithosphere (100 ppm) vs. the 558 million tonnes that have been mined between 1900 and 2010 (summing the USGS annual production figures) -- a ratio of over 24 million to one. --Many Minerals (talk) 04:29, 19 March 2012 (UTC)

## Minor inaccuracy regarding photography

In the modern use section, the daguerrotype is referred to as pre-photographic. Daguerre was actually not the first person to develop a photographic technique. His method is not pre-photographic. It is photographic, and the suffix pre- should be removed. Jdanielcloud (talk) 14:46, 27 March 2012 (UTC)

Thanks! Done! --Stone (talk) 19:03, 27 March 2012 (UTC)

## Where are chemical properties?

I copied following from Russian wiki:

${\displaystyle ~\mathrm {2Cu+H_{2}O+CO_{2}+O_{2}\longrightarrow \ Cu_{2}CO_{3}(OH)_{2}\downarrow } }$
${\displaystyle ~\mathrm {Cu+H_{2}SO_{4}\longrightarrow \ CuO+SO_{2}\uparrow \ +H_{2}O} }$
${\displaystyle ~\mathrm {Cu+2H_{2}SO_{4}\longrightarrow \ CuSO_{4}+SO_{2}\uparrow \ +2H_{2}O} }$
${\displaystyle ~\mathrm {2Cu+2H_{2}SO_{4}\ {\xrightarrow {200^{o}C}}\ Cu_{2}SO_{4}\downarrow +SO_{2}\uparrow \ +2H_{2}O} }$
${\displaystyle ~\mathrm {2Cu+2H_{2}SO_{4}+O_{2}{\xrightarrow {t^{\circ }}}\ 2CuSO_{4}+2H_{2}O} }$
${\displaystyle ~\mathrm {Cu+4HNO_{3}\longrightarrow \ Cu(NO_{3})_{2}+2NO_{2}\uparrow +2H_{2}O} }$
${\displaystyle ~\mathrm {3Cu+8HNO_{3}\longrightarrow \ 3Cu(NO_{3})_{2}+2NO\uparrow +4H_{2}O} }$
${\displaystyle ~\mathrm {3Cu+2HNO_{3}+6HCl\longrightarrow \ 3CuCl_{2}+2NO\uparrow +4H_{2}O} }$
${\displaystyle ~\mathrm {2Cu+4HCl+O_{2}\longrightarrow \ 2CuCl_{2}+2H_{2}O} }$
${\displaystyle ~\mathrm {2Cu+4HCl+O_{2}\ {\xrightarrow {500-600^{o}C}}\ 2CuCl_{2}+2H_{2}O} }$
${\displaystyle ~\mathrm {2Cu+4HBr\longrightarrow \ 2H[CuBr_{2}]+H_{2}\uparrow } }$
${\displaystyle ~\mathrm {2Cu+4CH_{3}COOH+O_{2}\longrightarrow \ [Cu_{2}(H_{2}O)_{2}(CH_{3}COO)_{4}]} }$
${\displaystyle ~\mathrm {Cu{\xrightarrow {NH_{3}\cdot H_{2}O,O_{2}}}\ [Cu(NH_{3})_{2}]OH\rightleftarrows \ [Cu(NH_{3})_{4}](OH)_{2}} }$
${\displaystyle ~\mathrm {4Cu+O_{2}\ {\xrightarrow {200^{o}C}}\ 2Cu_{2}O} }$
${\displaystyle ~\mathrm {2Cu+O_{2}\ {\xrightarrow {400-500^{o}C}}\ 2CuO} }$
${\displaystyle ~\mathrm {Cu+Cl_{2}\longrightarrow \ CuCl_{2}} }$
${\displaystyle ~\mathrm {Cu+Br_{2}\longrightarrow \ CuBr_{2}} }$
${\displaystyle ~\mathrm {Cu+S\ {\xrightarrow {CS_{2}}}\ CuS} }$
${\displaystyle ~\mathrm {2Cu+S\ {\xrightarrow {300-400^{o}C}}\ Cu_{2}S} }$
${\displaystyle ~\mathrm {2Cu+Se\ {\xrightarrow {300-400^{o}C}}\ Cu_{2}Se} }$
${\displaystyle ~\mathrm {4Cu+SO_{2}\ {\xrightarrow {600-800^{o}C}}\ Cu_{2}S+2CuO} }$
${\displaystyle ~\mathrm {2Cu+2NO\ {\xrightarrow {500-600^{o}C}}\ 2CuO+N_{2}\uparrow } }$
${\displaystyle ~\mathrm {4Cu+2NO_{2}\ {\xrightarrow {500-600^{o}C}}\ 4CuO+N_{2}\uparrow } }$
${\displaystyle ~\mathrm {Cu+2N_{2}O_{4}\ {\xrightarrow {80^{o}C,CH_{3}-COO-CH_{2}-CH_{3}}}\ Cu(NO_{3})_{2}+2NO\uparrow } }$
${\displaystyle ~\mathrm {2Cu+4KCN+2H_{2}O\longrightarrow \ 2K[Cu(CN)_{2}]+2KOH+H_{2}\uparrow } }$
${\displaystyle ~\mathrm {6Cu+12HCl+KClO_{3}\longrightarrow \ 6H[CuCl_{2}]+2KCl+3H_{2}O} }$

--Tim32 (talk) 20:43, 3 August 2012 (UTC)

## Arsenic

There probably should be a link to the related arsenic article. There are two instances of the "arsenic" word already, one of them probably should become that link? The page is locked, so I'll let a registered editor deal with this. Thanks, 76.10.128.192 (talk) 04:32, 24 October 2012 (UTC)

Done. SpinningSpark 13:56, 24 October 2012 (UTC)

## Incorrect Colored Metal Information?

I noticed that at the end of the section about Copper's physical characteristics, the article states that "Together with osmium (bluish), and gold (yellow), copper is one of only three elemental metals with a natural color other than gray or silver." However, when I checked the citation used to back up the claim, I could not find anything about Osmium being blue. As well, Cesium has a remarkably similar color to gold, making it also one of the only elemental metals with a natural color other than gray or silver. Now at the same time, I think Osmium doesn't really count; it only has a bluish tint, it's still rather silvery. So, I think a correct version would look similar to this: ″Together with cesium and gold (both yellow), copper is one of only three elemental metals with a natural color other than gray or silver.″ I hope this helps. 98.246.169.186 (talk) 01:56, 25 October 2012 (UTC)

Done Thank you! Double sharp (talk) 11:01, 25 October 2012 (UTC)

## Development of patina on architectural copper

I find the phrase "The final sulfate patina ..." somewhat perplexing, even though it reflects what appears in the (apparently) reliable sources quoted. One of these cited sources states:

Copper’s patination process is complex, involving initial formation of copper oxide conversion films, gradually interspersed over a number of years with cupreous and cupric sulphide conversion films, and culminating with conversion of the sulphide films to the green copper sulphate patina.

In architectural applications such as roofs it seems implausible that "cupreous and cupric sulphide conversion films" could form under the aerobic conditions of atmospheric exposure (this is more likely under anaerobic conditions, as biogenic sulfide corrosion); unless significant levels of H2S are present in the urban atmospheric environment e.g. due to emanations from sewers, I would have thought that reactions of copper oxides with carbonic acid (H2CO3, carbon dioxide dissolved in rainwater) would be more significant and ubiquitous.

A final "green copper sulphate patina" also seems unlikely. In the secondary enrichment processes that form supergene copper ore deposits, analogous copper sulphate minerals do form: chalcanthite (CuSO4·5H2O ) is highly water soluble, while antlerite (Cu3(SO4)(OH)4 ) and brochantite (Cu4SO4(OH)6 ) are particularly found in regions with arid climates.

For these reasons I would have expected that patinas formed in temperate climates would be dominated by basic copper carbonates similar in composition to malachite (Cu2CO3(OH)2 ), as was stated in the article prior to the latest edits by Enviromet. Cheers, Bahudhara (talk) 02:44, 13 September 2012 (UTC)

Thank you for your comments. I have researched the situation with multiple sources. The bottom line is that basic copper carbonates predominate as final patina products in unpolluted environments. In polluted environments, copper sulphates may predominate. Both copper carbonates and sulphates have been identified together as well, which is not surprising due to varying environmental conditions. I will revise this edit with multiple supporting references within the next 12 hours. Will do so in the Copper in Architecture article as well. Kind regards, Enviromet (talk) 04:47, 13 September 2012 (UTC)

That makes sense, Another source of sulphur in urban atmospheric pollution, from the Industrial Revolution until quite recently, would have been combustion of coal - this would have produced sulphur oxides, reacting with water vapour to form sulphurous or sulphuric acid. These would have reacted with the basic copper carbonate patinas directly, but without forming a sulphidic phase.
A technique in metalworking to produce a black patina on copper, is to bathe the metal surface with an aqueous solution of liver of sulphur (potassium sulphide) - the reaction is very rapid. So it's quite possible that hydrogen suphide in the atmosphere could have a similar effect over lengthy periods, even as a constant low-level emission from sewers. Cheers, Bahudhara (talk) 13:37, 13 September 2012 (UTC)

You are correct about the sulfur oxides from coal combustion and acid rain. Considering the small amount of space, I think it's best to just state that the final patina can be a mixture of sulfate and carbonate compounds, depending upon environmental conditions, such as sulfur-containing acid rain. To make it even simpler, the word "sulfur" could be taken out of the existing text altogether without any loss of meaning. What are your thoughts?

The chemistry could be explained in other articles, such as "Patina" and "Copper in Architecture." Some references I found on the chemistry of natural patinas, though not the textbook definitions I was looking for, include the following:

1) See definition for "patina" in: http://www.copperinfo.co.uk/resources/glossary.shtml

2) See discussion of patina chemistry in: http://www.wepanknowledgecenter.org/c/document_library/get_file?folderId=517&name=DLFE-2454.pdf

3) See mention of varying chemistries in: http://sg.answers.yahoo.com/question/index?qid=20090726064632AAiDf2k

4) Wikipedia article Copper(II) carbonate refers to a textbook (Masterson, W. L., & Hurley, C. N. (2004). Chemistry: Principals and Reactions, 5th Ed. Thomson Learning, Inc. (p 498)) but does not discuss sulfur as a component. http://en.wikipedia.org/wiki/Copper(II)_carbonate

5) This reference speaks of the green sulfate patina as mineral formulas: posnjakite and Brochantite http://www.sciencedirect.com/science/article/pii/S0010938X98000936

6) Finally, this reference only talks about sulfate in the final patina: http://www.copper.org/applications/architecture/finishes.html

Thanks again for your attention to this.

Sincerely, Enviromet (talk) 15:30, 13 September 2012 (UTC)

Unfortunately I don't have the time to follow this up just at this moment due to other commitments - however I am intrigued by the topic as it intersects with a number of my interests, including the biogeochemical reactions associated with acid sulfate soils.
In this context a major source of hydrogen sulphide is anaerobic microbial decay of organic matter in the coastal environment, which would be of particular importance in coastal or port cities, with Venice being a prime example. The article on the Horses of Saint Mark ends by mentioning corrosion due to air pollution; as a very famous artwork, it's quite possible that detailed studies of copper corrosion and patina formation may have been carried out during its restoration, and subsequently influenced the modern architectural literature.
It's also quite possible that the copper sheathing of wooden vessels would be affected by formation of a sulphidic film, particularly in polluted harbours, and so may have lead to earlier naval studies of the phenomenon. Cheers, Bahudhara (talk) 05:02, 14 September 2012 (UTC)

I modified the text as discussed and cited various references. I'll be on the lookout for a single solid reference that explains patina chemistry in both clean air and industrial environments, which will enable the removal of the multiple references cited here that explain various pieces of the puzzle. Thank you again. Enviromet (talk) 14:42, 14 September 2012 (UTC)

See verdigris --Chris.urs-o (talk) 04:28, 19 April 2013 (UTC)

## Spelling

If you're going to spell it "caesium", the colour is grey. MOS:RETAIN#Retaining_the_existing_variety suggests the default is set by the first non-stub article. Early versions of the article, back to the third revision ever used the British "coloured" spelling, but the very first used "color". I belive, however, that the first two revisions ("A chemical element, in the periodic table copper has the symbol Cu and atom number 29. Copper is a metal of red color. Copper oxide is green.") meets the definition of a WP:STUB ("an article containing only one or a few sentences of text that, although providing some useful information, is too short to provide encyclopedic coverage of a subject, and that is capable of expansion."), and thus British english is the default. 71.41.210.146 (talk) 10:49, 18 April 2013 (UTC)

I've just made it consistent as all but one use was "color". Seems it's been that way for quite a while, personally don't really care. You can discuss further here to seek consensus. Note caesium is covered under WP:CAES. Vsmith (talk) 14:38, 18 April 2013 (UTC)
Ah, thank you! I didn't know about that policy. My apologies. 71.41.210.146 (talk) 21:53, 21 April 2013 (UTC)

## Color

Copper is one of the only metals that is coloured,does anyone know why? If so could you add it. 04cah (talk) 13:51, 5 March 2009 (UTC)

Is the information under the color sub-heading isufficient? SpinningSpark 14:04, 5 March 2009 (UTC)
Color also discussed much further below at Talk:Copper#Incorrect_description_of_color_phenomenon. Rod57 (talk) 01:53, 10 March 2011 (UTC)
Could it not also say copper is pink because the stable oxide it forms in air is pink ie Cu2O
Also pure copper - what color is it - I've seen it fresh - being barely pink at all - is it possible that totally unoxidised copper is silver? —Preceding unsigned comment added by 213.249.232.187 (talk) 20:41, 3 April 2009 (UTC)

But it isn't silver. It is reddish, definitely, not silver. Scratch a penny made before 1982 and the fresh, exposed copper is pink. Pennies made in and after 1982 have zinc coated in a thin sheet of copper, so if you scratch one of those deep enough you can expose the zinc which is, in fact, silver color. The Seeker 4 Talk 01:23, 4 April 2009 (UTC)

Color of liquid copper needs clarification. The illustration says liquid copper looks pink in bright light, whereas the text says it's greenish. Certainly the hot liquid's incandescence is orange, so in the dark or in dim ambient light, liquid copper would appear orange. Bright ambient light, on the other hand, would reveal the liquid's true color. My guess is that liquid copper in bright light looks pink (like the solid) but in dim light it looks orange, by incandescence.CharlesHBennett (talk) 12:00, 16 February 2011 (UTC)

The colour of a copper absorption spectrum is pink (pink-red), definitely not orange-red as stated in the introduction. The mention of d electron transitions at photon energies corresponding to orange would result in an orange hue of fluorescent copper light, which is hardly what most people would understand by "colour". — Preceding unsigned comment added by 116.87.91.34 (talk) 04:36, 19 May 2013 (UTC)

## Copper bracelets and arthritis

There has been a lot of toing and froing over this in the article. We are at the point where we need to come to a decision on what we want in the article. Do we want the article to say that folklore believes copper bracelets relieve arthritis? Do we want to commnent on what medical science believes the efficacy of this treatment to be (as there once was with reference)? SpinningSpark 09:40, 10 June 2013 (UTC)

Related edits [8] (User:Nitrobutane), [9] (User:Spinningspark), [10] (Nitrobutane), [11] (User:Vsmith), [12] (Nitrobutane), [13] (User:JohnSRoberts99), [14] (Spinningspark), [15] (IP), [16] (User:Parcly Taxel), [17] (IP).

Let's get real. This article is about a hugely important element that had enormous importance in the development of human culture and technology and remains (and will continue to remain) of pivotal importance to human civilization. The question should be whether a wacky, unsupported belief involving a trivial use of copper with no measurable benefit to society merits a mention in this article at all. I vote to leave it out completely. Plantsurfer (talk) 10:37, 10 June 2013 (UTC)
In my opinion it would be better to make a separate entry for "Cultural usage and beliefs about copper". --Tobias1984 (talk) 12:32, 10 June 2013 (UTC)
Do you mean a separate article? Doubt that is needed, but maybe so.
Seems no one interested in the folklore bit about supposed arthritis symptom relief enough to find a WP:RS to support it. I am aware that copper bracelets and various magnetic thingys are hyped as cures or relief for various ills. However, we're not here to add to the hype. So quite simply, provide a solid reference to support or leave it out. Vsmith (talk) 15:38, 10 June 2013 (UTC)
I am not volunteering to write it, although it could be an interesting topic for the WikiProject_Rational_Skepticism. I am not sure if there is enough superstition for a whole article, but there might. Otherwise somebody could write up something about superstitions about the chemical elements. --Tobias1984 (talk) 15:53, 10 June 2013 (UTC)
Maybe a section in energy therapies or medical quackery? :) Vsmith (talk) 16:05, 10 June 2013 (UTC)
That would be a good place to put stuff like that :) --Tobias1984 (talk) 17:16, 10 June 2013 (UTC)
Preview shows some rational-looking discussion in Copper and the Skin By Jurij J. Hostynek, Howard I. Maibach. Search for 'bracelet'. William Avery (talk) 11:23, 11 June 2013 (UTC)
Chapter 10 is enjoyable, but I suggest this article on the element should not cover this topic. It is not fundamentally about copper the element, it is about arthritis in which, curiously, the supposed copper cure is not mentioned or it is about alternative medicine. Plantsurfer (talk) 13:25, 11 June 2013 (UTC)

it was admitted copper is of 'enormous importance in the development of human culture', and now you're completely disregarding a cultural belief regarding copper also I would appreciate it if these threats of blocking me stopped being used as a tool of manipulation--Nitrobutane (talk) 06:10, 12 June 2013 (UTC)

OK, I put it crudely. My point is it is about a belief that may or may not be rational, and not about the verifiable properties of copper. My point is also that while I acknowledge that this belief persists, this article on the element should confine its attentions to verifiable facts about copper, and the folklore issues should be reported elsewhere in Wikipedia IMHO. I believe that to be the consensus here. Plantsurfer (talk) 10:21, 12 June 2013 (UTC)
@Nitrobutane: I looked at your edits. I think the current consensus in Wikipedia is that certain bodies of information are kept separate in order to present a coherent picture. For example iron is separated from iron poisoning because of the same reason. We also have iron meteorite and meteoric iron (cultural usage of iron meteorites). I think we could support an article that reflects on the history and cultural usage of copper. Maybe even mention famous artifacts made from copper. That way the information you would like to add here, could have one or two paragraphs (modern cultural usage/beliefs about medical properties) and it wouldn't seem as much out of place in an article that discusses things like density, mass and electron configuration. --Tobias1984 (talk) 12:04, 12 June 2013 (UTC)

## Reserves - units

"As with many natural resources, the total amount of copper on Earth is vast (around 10^14 tons just in the top kilometer of Earth's crust, or about 5 million years worth at the current rate of extraction)."

Is there a source for this? Also, is it possible to avoid the use of the unit "ton" as it is defined in various ways. Use the SI tonne. — Preceding unsigned comment added by SheffGruff (talkcontribs) 12:27, 25 June 2013

## Too many refs?

Copper proteins have diverse roles in biological electron transport and oxygen transportation, processes that exploit the easy interconversion of Cu(I) and Cu(II).[102] [103] [104]

Why has this simple sentence suddenly acquired three refs? It looks like page-clutter to me and I am inclined to revert the change. I can think of several reasons why this was done, but with the lack of an edit summary I can only guess. If there is a problem with the original ref it should be replaced not added to. If the new sources contain useful further information beyond the sentence they are verifying then Further reading would be more appropriate. If the editor is associated with the inserted papers then posting here and leaving to other editors to decide to insert would be less controversial. SpinningSpark 10:21, 6 July 2013 (UTC)

## maximum permissible current density

"The maximum permissible current density of copper in open air is approximately 3.1×10^6 A/m2 of cross-sectional area, above which it begins to heat excessively.[6]"

While I'm generally for using SI units, this case might be misleading. Overheating depends on thermal insulation and while there was "open air" stated, bulk copper itself acts as thermal insulator but probably more significantly the specific surface area drops with wire diameter. So 3.1 A/mm2 are safe in air, I'm not sure about 3.1E6 A/m2, i.e. a wire with an actual cross section of 1 m2. You can have one or a few 1 m22 wires in free air, but one million wires with 1 mm2 in a dense bundle are no longer open air and will overheat at 3.1 A. Well, the one million wires need to maintain insulation from each other, while a 1 m2 "wire" could melt in the middle without much harm.

Yet, if you observe tables of maximum permissible current density you will see that the maximum permissible current density drops with cross section.Darsie42 (talk) 09:15, 14 August 2013 (UTC)

The max current density drops with cross-section mostly due to skin effect rather than inability to radiate the heat per se. Copper busbars more than about 3/4 inch thick are just a waste of copper, very little of the current will be in the interior. SpinningSpark 12:00, 14 August 2013 (UTC)

## Copper Vectoring

Im Artikel steht der Satz "Kupfer leitet den elektrischen Strom sehr gut (58 · 106 S/m)."
Das Kupfernetz der Deutschen Telekom in Deutschland besteht zu 100 Prozent aus Kupfer. Die elektrische Spannung V beträgt zwischen 60-70 Volt. Der elektrische Stromfluss A ist variabel (Elektronik bis 5 Ampere). Die Bundesnetzagentur hat entschieden, dass im Netz der Deutschen Telekom der Bitstrom (Datenpakete) mit 100 MBit/s (300 MBit/s - Leitung/virtuelle Leitung/Leitung-) fließen soll. Dazu investiert die Deutsche Telekom ab 2013 zirka 200 Euro pro Haushalt, bei 24 Millionen Haushalten sind das 4,8 Milliarden Euro. Dabei wird die Kabelverteilertechnik in 330.000 Kabelverteilern in Deutschland durch Technik der Firma Alcatel Lucent ersetzt. Auf Seiten der Telekomkunden und Mitbewerberkunden werden entsprechende 100 MBit/s-Modems benötigt. 93.229.148.172 (talk) 01:28, 5 September 2013 (UTC)

Machine translation:
In the article, the sentence is "Copper conducts electricity very well (58 · 106 S / m)."
The copper network of Deutsche Telekom in Germany consists of 100 percent copper. The voltage V is between 60-70 volts. A flow of electric current is variable (electronics to 5 amps). The Agency has decided that the network of Deutsche Telekom, the bit stream (data packets) with 100 Mbit / s (300 Mbit / s - Cable / virtual Leitung/Leitung-) to flow. The German Telekom is investing about 200€ from 2013 per household, with 24 million households are 4.8 billion euros. The cable distribution technology is used in 330,000 cable distributors in Germany replaced by technology from Alcatel Lucent. On the part of customers and competitors to telecom customers relevant 100 Mbit / s modems are required.
Do you have a suggestion for improving the article? SpinningSpark 10:58, 5 September 2013 (UTC)

## Semi-protected edit request on 9 April 2014

There is no source for this, and this is not confirmed anywhere in literature:

"Natural bronze, a type of copper made from ores rich in silicon, arsenic, and (rarely) tin, came into general use in the Balkans around 5500 BC." 150.212.46.94 (talk) 15:49, 9 April 2014 (UTC)

Done Jackmcbarn (talk) 18:42, 9 April 2014 (UTC)

## Semi-protected edit request on 12 May 2014

In the History section of the infobox, the entry for Discovery reads "Middle Easterns (9000 BC)". This should presumably read "Middle East (9000 BC)". 130.216.218.47 (talk) 02:44, 12 May 2014 (UTC)

Done. -DePiep (talk) 03:29, 12 May 2014 (UTC)

## Bone char absorbs copper

Bone char presents high absorptive capacities for copper. [3][4][5] [6]

References

1. ^ Pipex Pharmaceuticals Initiates Phase II Clinical Trial of Anti-Copper COPREXA for Alzheimer's Disease
2. ^ Cite error: The named reference undefined was invoked but never defined (see the help page).
3. ^ "Chemical fixation of metals in soil using bone char and assessment of the soil genotoxicity". February 2007. Unknown parameter |Author= ignored (|author= suggested) (help)
4. ^ Wilson, J.A., Pulford, I.D. and Thomas, S. (2003). "Sorption of Cu and Zn by bone charcoal". 25. Environmental Geochemistry and Health: 51–56.
5. ^ Choy, K.K.H. and McKay, G. (2005). "Sorption of metal ions from aqueous solution using bone char". 31. Environment International: 845–854.
6. ^ “Bone Char” Wikipedia Contributors, Wikipedia, The Free Encyclopedia accessed 11/17/2013 available at: https://en.wikipedia.org/wiki/Bone_char
As I said in my edit summary removing it, that is a property of bone char, not a property of copper. SpinningSpark 02:46, 19 November 2013 (UTC)

I think it is important to show how elements are bioremediated and that this information is best presented on the page of the pollutants themselves; in this case copper. That way the information can be more easily accessed by someone with a copper pollution problem, who doesn't already know about bone chars absorbitive capabilities from studying bone char. I have no intention of adding this information again; but it should be one the page, the same information is now up on the pages for zinc and cadmium. CensoredScribe (talk) 04:59, 19 November 2013 (UTC)

Not any more it isn't. SpinningSpark 02:40, 20 November 2013 (UTC)
Being argumentative will get us nowhere fast. As a point, if two substances react in any way, it is not a result of the properties of only one constituent of the reaction; both parties in a reaction possess a property that causes them to react. For instance, while bone char may exhibit a high absorptive capacity for copper, it may not for other substances. While mentioning bone char's properties specifically in copper's article may not be an optimal choice, mentioning copper's group 12 potential for absorption by activated carbons may be a useful addition - it is, in fact, pertinent to copper as an element. 2602:252:D5C:36B0:B476:8D0D:4866:506E (talk) 16:45, 19 October 2014 (UTC)

## Density Units

The unit used to measure copper's density in the infobox at the right of the article is g/cm-3, which is extremely misleading. Copper's density is 8.96 g/cm3. The minus is completely extraneous and confusing. I won't edit myself, in case there are objections, but I feel that somebody ought to. 2602:252:D5C:36B0:B476:8D0D:4866:506E (talk) 16:49, 19 October 2014 (UTC)

You can't edit the article because it is protected and you are not a registered user. But in any case the format of the element infoboxes is set in the element infobox template, not here. Changes will effect multiple articles and should be discussed first at Wikipedia:WikiProject Elements. In any event, you are misreading the infobox. The units are g·cm−3 which means grammes times metres to the minus 3, not divided by. This is a pretty standard form of writing units in scientific literature. By only using multipication it avoids division and the consequent order of precedence issues which might otherwise require brackets to resolve, or else cannot be presented on a single typed line. SpinningSpark 15:39, 22 October 2014 (UTC)

## Nucleosynthesis

I have a proposal that I'd like to discuss. If the community agrees with this proposal, I'm happy to do the work or not as people see fit.

What I'm proposing is that articles about elements should, in their stat block at the top of the article, include stats and links about that element's nucleosynthesis, to explain where the element comes from. The source of an element is as essential a piece of information as its atomic number or other characteristics, since it explains where all of these other characteristics came from. I spent an hour and a half today hopping from article to article trying to track this down for the element copper, and it was not nearly easy enough to find for something so essential.

Wikipedia has excellent articles on nucleosynthesis in general, and it has this (http://en.wikipedia.org/wiki/Nucleosynthesis#mediaviewer/File:Nucleosynthesis_periodic_table.svg) table, which is very helpful, but what's missing is an expansion of the story of each element specifically. For example, copper is shown in the table as coming from "Large Stars," and Wikipedia has a useful article about the s-process involved, the linkage between the two is missing, as is any direct linkage between the article about Copper, the article about the s-process, and that table. I had to search off Wikipedia to document the connection, which I did thanks to this (http://kencroswell.com/Copper.html) page. Ken Croswell's article about the nucleosynthesis of copper is excellent

Ideally, each element should have some reference to its nucleosynthesis in its stat block, and should include either a section in the article or a page called "Nucleosynthesis of Copper" (for example) that puts what's known about it into words. All these element pages should be linked together by category pages for each nucleosynthesis process, e.g., the Copper page should be referenced in a category page called s-process Elements, along with all the other elements nucleosynthesized by the s-process, and so on.

Wikipedia's articles about nucleosynthesis include some helpful diagrams that illustrate the "genealogy" if you will of selected elements. Each element should have this treatment, including a diagram that shows its complete pedigree from hydrogen and lists the processes involved. This should be done in a way that exposes the cosmic perspective, not just the chemistry, so anyone looking at the copper coating of a modern U.S. penny, for example, can be inspired to think about the astonishing cosmic events - big bang and stellar births and deaths - that had to take place for this humble penny to exist - and thence to appreciate also our own remarkable pedigree.

This overhaul of the format and content of each element page, creation of category pages, and cross-linking would be a moderately sized project up front, but since our understanding of the elements is so relatively stable compared to other subjects, it would be unlikely to impose much of a maintenance burden going forward after its initial completion.

How does the community feel about a project like this?

This is my first time seriously proposing a change to Wikipedia, so I apologize for any errors in protocol I might be making.

Toad4242 (talk) 22:49, 11 November 2014 (UTC)

Your project is one I've been going to do for some time, but it's a added paragraph for most of our elements, and is some work. Some of this has been done. Look at deuterium, helium or even nickel and you'll see a nucleosynthesis section, usually in the isotopes section. In other articles, it begins the "occurrence" section as "cosmic occurrence," where we discuss Milky Way and crustal abundance before minerals and ores.
A lot more is known about nucleosynthesis than was known in the BF^2H times, but there are good summaries, and the the one I was planning to use was a summary paper used to generate a table in McSween and Huss' text Cosmochemistry pp. 104-108. It has cosmic origins for elements and processes taken from Anders and Gravisse, 1989. Abundances of the elements: meteoric and solar. Geochemica et. Cosmochemica Acta 53, 197-214.
Once something like this table is available, it needs to go in the appendix as embedded list in the articles on nucleosynthesis, and the same table with origins should complete the set of stable nuclides. If you get a monograph on nucleosynthesis of the range of isotopes of some element, as you occasionally do, you can use it to flesh out the main article on isotopes of xxxx which we have for each element. Then a paragraph or so of that can go in the late "isotopes" or early "occurrence" sections of element articles that don't have them now. And yes, the infobox has room enough for and R or S or one over the other (Rs) or letters for the few other processes that we know of (light element burning or fusion, big bang, spallation, explosive synthesis, etc).
So go for it. You'll probably see my steps occasionally where I've used the source above to tag elemental sources. SBHarris 23:14, 11 November 2014 (UTC)

## Menke's Disease deficiency of copper

http://en.wikipedia.org/wiki/Menkes_disease also a recessive inherited disease. I have posted a paper on Google Drive where I posit this damage occurred in the population of Doggerland due to radon exposure chromosomal damage. 24.50.151.151 (talk) 13:49, 1 December 2014 (UTC)

"64Cu is a radiocontrast agent for X-ray imaging, and complexed with a chelate can be used for treating cancer. 62Cu is used in 62Cu-PTSM that is a radioactive tracer for positron emission tomography.[14]". Typically compounds of non-radioactive heavy elements like Ba and I are used as radiocontrast agents. The rather weakly radioactive element Th has been used but this often resulted in cancer after a few decades. The amount of Cu64 required to produce an x-ray absorption contrast would kill the patient quickly. It is likely that 64Cu like 62Cu is used in positron emission tomography although other radiotracer methods could be possible. I can't provide any references but the indicated use as an (absorption) radiocontrast agent is quite unreasonable. Unfortunately editing of the article seems to be blocked but let's hope the article is frequently updated based on talk comments.150.227.15.253 (talk) 13:25, 14 April 2015 (UTC)

I removed the statement that you are questioning. I'm not sure what its intended meaning is either. FWIW, in the future, you can use {{Edit semi-protected}} which will tends to get more notice. ChemNerd (talk) 16:35, 14 April 2015 (UTC)

## Copper does not absorb red or orange light

'The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells is such that it corresponds to orange light.'

This is obviously incorrect. If it were so, then copper would be a green material.

I did not find an absorption spectrum for Copper, just for gold. There, most of the absorption occurs in the UV, dropping off between 600 and 500 nm; at energies lower than 500 nm, reflectivity is ≈100%. I guess in copper it would be similar, with visible light higher in energy than 500 nm be blocked.

The article seems to be blocked from editing, so I cannot change it. 27.34.97.183 (talk) 19:49, 14 April 2015 (UTC)

## copper through the skin

• Hostýnek, Jurij J.; Dreher, Frank; Maibach, Howard I. (2006). "Human stratum corneum penetration by copper: In vivo study after occlusive and semi-occlusive application of the metal as powder". Food and Chemical Toxicology. 44 (9): 1539–1543. doi:10.1016/j.fct.2006.04.003. ISSN 0278-6915.

Is there a chance that there is a little bit going through the skin?

--Stone (talk) 20:48, 30 March 2016 (UTC)

## Semi-protected edit request on 11 April 2016

Small "typo": The BC in the last date of second (overview) paragraph is missing:

Current state:
Copper is found as a pure metal in nature, and this was the source of the first metal to be used by humans, ca. 8,000 BC; it was the first metal to be smelted from its ore, ca. 5,000 BC; it was the first metal to be cast into a shape in a mold, ca. 4,000 BC; and it was the first metal to be purposefully alloyed with another metal, tin, to create bronze, ca. 3,500.[1]

New version (just "BC" added after 3,500 ):
Copper is found as a pure metal in nature, and this was the source of the first metal to be used by humans, ca. 8,000 BC; it was the first metal to be smelted from its ore, ca. 5,000 BC; it was the first metal to be cast into a shape in a mold, ca. 4,000 BC; and it was the first metal to be purposefully alloyed with another metal, tin, to create bronze, ca. 3,500 BC.[1]

References

1. ^ a b McHenry, Charles, ed. (1992). The New Encyclopedia Britannica. 3 (15 ed.). Chicago: Encyclopedia Britannica, Inc. p. 612. ISBN 085-229553-7.

134.100.110.218 (talk) 11:41, 11 April 2016 (UTC)

Thanks! Nicely spotted.--Stone (talk) 13:21, 11 April 2016 (UTC)

## Semi-protected edit request on 20 April 2016

There's a small calculation mistake on the introduction page of the article:

The adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight. Hence a healthy human weighing 60 kilogram contains approximately a tenth of 0.1g of copper.

Last sentence should be corrected to "approximately 0.1g of copper" (remove "a tenth of").

Thanks, Uri Rimon Uri (talk) 10:55, 20 April 2016 (UTC)

Done thanks for pointing that out - Arjayay (talk) 11:10, 20 April 2016 (UTC)

## Resulting alloys?

This sentence needs clarification or rewording. I do not have the source, but hoping someone does. Thus: "Copper is one of the most important constituents of carat silver and gold alloys, and carat solders are used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys." Solder would not modify the base alloy, except at the junction. But the junction is not usually large enough to worry about color or color change. The statement is a little confused. Grammar's Li'l Helper Talk 17:10, 3 June 2016 (UTC)

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