Talk:Cobalt

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Good article Cobalt has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
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Article changed over to new Wikipedia:WikiProject Elements format by Dwmyers 16:31 Feb 20, 2003 (UTC). Elementbox converted 14:57, 2 July 2005 by Femto (previous revision was that of 00:39, 15 May 2005).

Information Sources[edit]

Some of the text in this entry was rewritten from Los Alamos National Laboratory - Cobalt. Additional text was taken directly from USGS Cobalt Statistics and Information, from the Elements database 20001107 (via dict.org), Webster's Revised Unabridged Dictionary (1913) (via dict.org) and WordNet (r) 1.7 (via dict.org). Data for the table was obtained from the sources listed on the subject page and Wikipedia:WikiProject Elements but was reformatted and converted into SI units. —The preceding unsigned comment was added by Dwmyers (talkcontribs) 16:31, 20 February 2003 (UTC)

K.H.J. BUSCHOW (ed.), Handbook of magnetic materials, volume 12, 1999 Elsevier page 126 for the hcp->fcc transition. —The preceding unsigned comment was added by Marc Tobias Wenzel (talkcontribs) 17:01, 20 May 2003 (UTC)

Cobalt bomb?[edit]

Wasn't there some fear back in the '50s (on up to the '70s, as I recall it mentioned on The Bionic Woman of all things) that a Cobalt bomb could destroy the atmostphere of the earth? Would be interesting to see some discussion of that here. A brief search on Google turns up nothing. (now that I spelled it right (habit from correcting people who spell COBOL cobolt!) I found several references: Leo Szilard called the cobalt bomb a "doomsday" device since it was capable of wiping out life on earth.)-justfred —The preceding comment was added on 16:24, 20 December 2001.

See wikipedia's hydrogen bomb or nuclear weapon - "Another variant uses Cobalt in the shell, and the neutrons convert the Cobalt into Cobalt 60, a powerful long-term emitter of Gamma rays. The primary purpose of this weapon is to create extremely radioactive fallout to permanently deny a region to an advancing army, a sort of wind-deployed mine-field. It was actually tested by the British in Central Australia, in areas that remain uninhabitable to this day." The fears over destroying the atmosphere were applied to the first atomic tests. —The preceding unsigned comment was added by 62.253.64.xxx (talkcontribs) 16:34, 20 December 2001 (UTC)

Note that 'central Australia' and 'inhabitable' are just about idiosyncratic to start with; marginally more friendly than Mars, if only because it has a breathable atosphere. --Zatnik (talk) 08:46, 4 May 2008 (UTC)

MSM: actually the cobalt-salted bomb became the ultimate terror weapon, and its qualities continued to change and grow more fearsom with every telling. After Szilard foolishly referred to it as a "doomsday device" it was all downhill from there.

Basically he was trying to demonstrate that there are particular effects of bombs that could render an area useless to humans, and the several-year-deadly fallout from a cobalt bomb was the perfect example. What needs to be clear is the amount required though, the Earth is a VERY big place! If you consider a 10ft radius bomb containing powder, you'll see the problem.

However once it was out, it was out. Soon you had all sorts of stories of a single bomb going off and wiping out the entire planet forever. But that wasn't enough, and new and more interesting effects were then invented for it, including what you note above. —The preceding unsigned comment was added by Maury Markowitz (talkcontribs) 18:06, 6 September 2002 (UTC)

CMB: Along with "nuclear winter," part of the repertoire of public stone age superstition about nuclear war. Cobalt weapons produce longer lived by-products and would require longer stays in shelter. To achieve the science fantasy consequences of ON THE BEACH, it would be necessary to detonate a bomb with a cobalt warhead about the size of the moon, so it seems it might be easier to just drag the moon into the earth if you wanted a maximum result in fatalities.

A lot of this stuff, once registered in the feeble collective unconscious of mankind, is there to stay and common sense doesn't stand a chance of dislodging it. —The preceding unsigned comment was added by 211.27.131.67 (talkcontribs) 01:36, 9 October 2004 (UTC)

MV: I have seen in some websites that the cobalt could not be placed in the shell as in order to absorb the biggest amount of neutrons, it would have to be in the tamper. And t is claimed that 33.6 tons would be enough to cover all the earth's landmasses. Is there some validity to that? --151.198.130.79 03:23, 17 January 2006 (UTC)

Correct. Szilard's idea was that the tamper would contain the cobalt where a more "traditional" bomb would contain additional fissionable materials. Most radioactive fallout will precipitate out of the atmosphere in a matter of days, but the fallout created by a so-called cobalt bomb remains suspended in atmospheric gases, so that it remains radioactive until it decays into a non-radioactive form. Sziland further proposed that the bomb itself should work by hydrogen fusion rather than the famomiliar fission method, hence the term "hydrogen-cobalt bomb". Given the greater power of hydrogen fusion as opposed to fission, Szilard estimated that 500 "hydrogen-cobalt bombs" could destroy the population of the world. Notice he says COULD, not WOULD. And when he says that, he optimizes the spacing of the detonations relative to one another. Nonetheless, he's right. You could indeed create a situation in which global wind patterns would carry the fallout around the globe and create enough fallout that the entire atmosphere of the earth would become lethally contaminated in two or three years, and we'd all die of radiation poisoning. Szilard suggests that the cobalt would decay to a harmless isotope thereof in about twenty years, so presumably if you could shelter yourself underground for that long you could survive. More recent studies, however, suggest that it might take several times that long for the decay to take place, and that you might have to shelter yourself for fifty, a hundred or several hundred years. That part is disputed. The earth, as a correspondent has stated above, is a big place, but the power of hydrogen fusion is also big. The bottom line is that it's a question of amount. "The size of the moon" is a strange estimate, given the power of fusion. Tom 129.93.17.115 03:20, 6 December 2006 (UTC)

Covert Iron into Cobalt?[edit]

~~MV~~

I think there has been a little mistake in the article. The way is written gives the impression that any iron (and therefore steel) would turn in great part or totally in Cobalt 60. I think it would be better to clarify that cobalt 59 turns into cobalt 60 by the emission of neutrons, not any iron or steel, (there is a mention in the article of natural cobalt being able to be converted even in large quantities by exposing cobalt to neutrons, not iron or steel). Many nuclear weapons tested used steel cases and they did not all turn into cobalt 60 (Ivy Mike, for example). Some cobalt 60 results as part of the fission products and due to the use of cobalt in some alloys, but it is not all or in great part cobalt 60. The mention of iron turning into cobalt 60 can be kept, but it could probably be stressed that it would be a small amount, like other fission products. That also could point out as the next sentence intends that some nuclear weapon designs could increase the amount of cobalt 60 by using cobalt 59, rather than steel or other casing which would not produce much cobalt 60. I think that change could be made. --Mike Velasquez 01:20, 23 February 2006 (UTC)

This appears to have already been fixed. If you feel there's still a problem, please indicate where it is, because the section discussing cobalt bombs indicates that the source of cobalt 60 is cobalt 59. By the way, you might want to consider creating a user account; it will give you a user page to put any personal information you desire, and a user talk page where others can get ahold of you. --Christopher Thomas 07:26, 25 February 2006 (UTC)

Thanks for the advice, I will consider creating an account. Don't worry, There is no problem , just thought that the mention of iron turning into cobalt should not have been changed completely for Cobalt 59, only specified that the amount of cobalt 60 would be very small with iron (and wouldn't be a more significant risk than other fission products), and then contrast it with the risk of cobalt 59 being used in a bomb. --68.162.16.204 18:44, 25 February 2006 (UTC)

kobalos[edit]

My entry from Lidell and Scott:

Κόβαλος, m, an impudent rogue, arrant knave, Ar.: -Κόβαλοι were mischievous goblins, invoked by rogues, Id.
II. as adj Κόβαλα, knavish tricks, rogueries, Id.  (Deriv. uncertain)

I don't in the slightest dispute that Κόβαλος is the fons of goblin, kobold, kobalt, cobalt, etc, but can someone show me a source for Κόβαλος meaning "mine"? For mine, I find this and these [1].--Josh Rocchio 01:00, 5 June 2006 (UTC)

The/one source appears to be http://elements.vanderkrogt.net/element.php?sym=Co. No idea how, or if, this holds up to your cites. You appear to know what you're talking about, do what's necessary to the article. Femto 11:28, 5 June 2006 (UTC)

c/a-ratio[edit]

I miss the c/a-ratio of hcp-cobalt. Does anybody know? SietskeEN 08:26, 22 July 2006 (UTC)

Never mind, I already found it: the lattice constants a and c are 2.5071 and 4.0695 Å, therefore c/a is 1.623. SietskeEN 08:30, 22 July 2006 (UTC)

Decay energy of 57Co[edit]

The article states that the decay energy of Co57 is 0.833 MeV. However, I use it all the time and know that the 272-day decay produces a 122 KeV photon (and a 133 KeV with much lower probability). This is also the result of the nice applet at: http://www.nndc.bnl.gov/nudat2/indx_dec.jsp. Is the value currently printed here (0.833) a typo?

Answer to my own question: The value stated here in the decay energy (he kinetic energy available for all the decay products. This value is indeed much greater than the energy of the emitted gamma. Apparently, most of the energy for this decay is carried off by a neutrino.--PloniAlmoni 09:43, 16 November 2006 (UTC)


Image of cobalt metal[edit]

Is the image of cobalt metal included in this article really cobalt? I looked online for more images of Cobalt metal and all the other pictures I have seen look much more silvery and much less golden.


Hey Guys

In medical uses of cobalt you should mention its use as an Implant material. Its used as for dental implants when alloyed with chromium and molybdenum, refered to as "CoCrMo" in scientific journals or "Vitalium" as a tradename

cheers

Chris


Cobalt in Biology[edit]

Apart from Cyanocobalamin (vitamin B12), is cobalt an essential trace element for humans or other organisms? Icek 17:10, 17 April 2007 (UTC)

Shouldn't Cobalt be in Category:Biology and pharmacology of chemical elements ? Eldin raigmore (talk) 20:31, 16 May 2009 (UTC)

Quincy, ME[edit]

In the episode of "Quincy, ME" called "An Unfriendly Radiance", there is are plenty of references to Cobalt in radiation. One particular use that was mentioned was checking building structure integrity after earthquakes. The information on the main page seems to support this use. Is this a real use of cobalt radiation? If not, it makes for interesting trivia. —Preceding unsigned comment added by 203.220.148.111 (talk) 23:56, 2 December 2007 (UTC)

Cobalt Atomic Mass?[edit]

I don't think it was mentioned in the article, does anyone know the Atomic Mass of Cobalt? If it was mentioned...whoops. --RobertLeBlais (talk) 14:58, 7 January 2008 (UTC)

It was: "Standard atomic weight 58.933195(5) g·mol−1 " (On Earth, atomic mass = atomic weight) --Zatnik (talk) 08:38, 4 May 2008 (UTC)

References[edit]

Cobalt mines?[edit]

Are there cobalt mines in real life? Angie Y. (talk) 20:01, 10 June 2009 (UTC)

The important cobalt mines are not 100% cobalt mines. Most of the cobalt is extracted from copper and nickel mining. The Katanga province of southern congo is the best example for the copper ores rich in cobalt. If you want to know more look at the two references from the USGS number 7 and 8 in the article itself.--Stone (talk) 20:59, 10 June 2009 (UTC)
Found in the refs that marocco has some mines only dedicated to cobalt mining.--Stone (talk) 21:01, 10 June 2009 (UTC)
See, in Mortal Kombat: Conquest, the realm of Outworld has a mine-prison called the Cobalt Mines of Shokan. From what I can gather, the miners/prisoners only mine pure cobalt, treatment of prisoners is quite harsh, and that lungs give out from dust in the mines. Angie Y. (talk) 01:36, 11 June 2009 (UTC)

Isotope stability considerations[edit]

27Co Cobalt is the 7th element in the so called "Transition Metal" series of the periodic table. Of the 10 elements in that series, 3 are "Monisotopic", with only 1 stable isotope, and a fourth has only a very minor (0.3%) constituency of a second stable isotope. Accordingly, the stability indicating proton/neutron constituency of the stable elements in this area are pretty well defined. The first element, 21Sc Scandium is noted to be stable at Mass number 45 with 24 neutrons, or with 3 "extra neutrons" beyond the 21 that could be paired with the 21 protons. It is accordingly an OE or odd-proton even-neutron type of element. The rest of the odd Z elements have a majority of their stable constituents with an "extra neutron" quantity of 5. And the heaviest element 29Cu has a minority (31%) of its stable element constituency with an extra neutron value of 7. On the other hand, the even Z number elements of this series are all able to be stable with a lower number of excess neutrons; with element 28Ni be noted to have a 68% constituency of its stable isotopes as 28Ni58 with only 2 extra neutrons. The even Z elements also have a greater number of stable isotopes with mostly 4 extra neutrons but also with greater numbers ranging up to 30Zn70 which is stable with 10 extra neutrons. This stability with extra neutron tendency in this area is evidently a part of the transition properties of these elements, which are subsequently followed in the periodic table by the next 6 element series, where the extra neutron requirement for stability is increased at the rate of nearly 2 neutrons/Znumber up to a maximum of 14 extra neutrons for the inert gas element 36Kr86. It is therefor pretty apparent that the isotopic stability in this area is achieved by increasing the number of neutrons at a greater rate than that for the increase in the number of the protons and the Z number. And it appears that the number of "extra neutrons" rather than the total number of neutrons is a more important factor in explaining these relative stability considerations.WFPM (talk) 22:58, 9 September 2009 (UTC)

Pronunciation[edit]

The Oxford English Dictionary says /'kəʊbɒlt/. The pronunciation in the article, /ˈkoʊbɔːlt/, is odd.213.122.50.186 (talk) 18:58, 16 July 2009 (UTC)

I've updated the pronunciation (both the IPA and the phonetic) to reflect what is actually contained in the Oxford English Dictionary. The correct pronunciation is 'KOH-balt', with the 'bal' sounding like 'ball'. —Preceding unsigned comment added by 82.25.235.78 (talk) 20:25, 28 July 2010 (UTC)

the cause of the cobalt blue color?[edit]

I am rather sceptical about the following assertion: " Cobalt blue (cobalt(II) aluminate, CoAl2O4) gives a distinctive deep blue color to glass, ceramics, inks, paints, and varnishes."

I am right now (2009-11-08) employed at the Blaafarveværket in Norway, and working on a display on cobalt.

The proces used for producing the blue pigment at the Blaafarveværket is well-described and cannot be doubted.

Cobalt oxide was smelted together with quartz and potassium carbonate. The result was an intensive blue glass-like substance that was grounded and sold to producers of glassware and porcelain.

The proces is described in Tone Sinding Steinsvik's book "Koboltgruvene og Blaafarveværket", ISBN 82-90734-20-4.

It can very well be that modern production methods favour cobalt aluminate, but obviously this hasn't always been the case. I feel very much tempted to edit this section, but will wait a couple of weeks in case someone with even more knowledge about this issue can put things in perspective.

Ron Werner (talk) 22:04, 8 November 2009 (UTC)

There seems to be two types of cobalt colouring materials: Smalt and Cobalt blue, while smalt [2] [3] is the silicate the cobalt blue of Tennard is the aluminate. For the painting mostly the Cobalt blue is used while for colouring glas mostly smalt is used. Has to be cleared out.--Stone (talk) 22:25, 8 November 2009 (UTC)
I added a little bit to make the whole thing clearer, but if you want and what ever you think is necessary.--Stone (talk) 11:52, 9 November 2009 (UTC)

Origin of the Name[edit]

Cobalt is believed to be named after Kobolds by German miners who believed the creatures to have cursed silver and turned it into Cobalt. —Preceding unsigned comment added by Fawkes-nvmbr5th (talkcontribs) 05:55, 2 January 2010 (UTC)

I was told by my metallurgy lecturer at University that the elements Cobalt and Nickel were so called during the early years of steelmaking. The presence of these metals in the iron ore spoiled the steel but their existence was unknown - hence "Kobolds" or "Old Nick" (the Devil) was blamed for the failure. Once the elements themselves were discovered the names were kept. Pdelle (talk)

Awful English[edit]

Protection of this page is kind of annoying. Consider the "Pigments and Coloring" section. I would like to change "Since the midage the production of smalt a blue colored glas was known." to "Since the middle ages, cobalt oxides have been used in the production of smalt, a blue-colored glass." Someone change this, or I will once I make enough edits to change semi-protected pages. ThomYorke64 (talk) 16:22, 13 January 2010 (UTC)

I have unprotected the page for now. Please feel free to make your improvements to the article. -- Ed (Edgar181) 16:25, 13 January 2010 (UTC)
Already corrected.--20:41, 14 October 2010 (UTC)

this phrase is also wrong

"These were named for problematic Earth-spirits, because they appeared to be ores of copper or nickel, but in simple smelting yielded no metal, but gave poisonous fumes."

207.253.74.149 (talk) 09:50, 17 November 2010 (UTC)

Thanks, quick-fixed. The article is yet unshaped. Materialscientist (talk) 10:06, 17 November 2010 (UTC)

Cobalt Sourced from Congo[edit]

I'm extremely dubious about the sources given in regards to Cobalt mining's dependence on the Congo. Source 26 doesn't work, Google "African Mineral Production" and it's the first result. However, this source does not mention 40% supply from the Congo, the figure it does give is drastically less than 40%, and reduced rapidly to 2005. Also, 2005 is a long time ago, this source is now unreliable. My second problem is with Source 27, which claims: "The effect of rising prices as a driving force on finding new solutions to mineral resource sustainability is well demonstrated by the cobalt supply shortage resulting from the political Shaba crisis in Zaire in 1978. This crisis caused the price of cobalt to skyrocket. Zaire, now the Democratic Republic of Congo, is the world’s largest cobalt producer". 1978 is not recent evidence. 86.21.27.176 (talk) 18:08, 2 November 2010 (UTC)

2005 is not long ago for an element discovered centuries ago. The problem is always that even the newest publications in 2010 would only give the numbers of 2008. The dependence on the congo is hard to prove, because people producing and delivering from the congo will try to hide what they are doing because conflict mineral and coltan give you a very bad image as a company if you buy from congo sources. The numbers given are mostly estimates and they change with the state of crisis.-Stone (talk) 19:28, 2 November 2010 (UTC)
The cobalt crisis is one of the major examples for a shortage of supply and rising price yielded much lower demand even after the supply was re-established and therefore a much lower price. -Stone (talk) 19:28, 2 November 2010 (UTC)
Please check source 26, it doesn't mention 40% or any fractional representation of this at any point. It gives a value for extracted Cobalt, which reduced compared to other countries rapidly towards 2005. So the source itself suggests that the DRC did not supply 40% of world usage in 2005.. in addition to a trend of rapid reduction.
Source 27 is also questionable, as source 26 clearly shows a rapidly changing trend in supply over a 5 year period ending in 2005, let alone how much things have changed since 1978.
Unless anyone has some additional sources for these claims, I really don't see how they can remain in the article. 94.195.49.62 (talk) 17:22, 7 November 2010 (UTC)
There is good source for all the data you want:

USGS Here a little table: The only thing I do not like is that one time the table is for thousand pounds and than for short tons and later for metric tons.

Table caption
Zambia Congo World
1964 1571 8461 19075
1965 1702 9246 20312
1969 1997 11680 21778
1973 4740 16592 32428
1974 4230 19436 35791
1975 2625 15430 32462
1976 2398 12100 23609
1977 1878 11600 23609
1978 4124 14660 29771
1979 4718 16530 32928
1980 4850 17000 34178
1982 7167 24900 54162
1983 7052 24900 52297
1984 10185 39700 71756


This source claims 20% in 2003 www.bgs.ac.uk/downloads/start.cfm?id=1419 (Source: World Mineral Production)
This source claims 28% in 2003 http://www.indexmundi.com/en/commodities/minerals/cobalt/cobalt_t8.html (Source: United States Geological Survey Mineral Resources Program)
That second source also cites 41% production for 2006, which is odd seeing as the source cited in this article (World Mineral Production) suggests a reduction in production leading to 2005, not an increase. I think the problem here is the definition of "production" - some sources are claiming production is the mining of raw Cobalt, whereas others are claiming it is where the Cobalt was refined. As someone's already mentioned, knowing where it is mined is very difficult, mostly we can only see figures for where it was refined.
Though it's undeniable that the vast majority of sources suggest a large portion of Cobalt is refined in the DRC, putting a figure of 40% on it can be misleading. I would like to include a few different sources showing large Cobalt production in the DRC, and amend it to simply state that the DRC "is the largest exporter of Cobalt in the world" with no figure. 94.195.49.62 (talk) 11:23, 8 November 2010 (UTC)

density of cobalt[edit]

In the common literature the density for cobalt is called between 8.830 g/cm^3 and 8.9 g/cm^3. A rather wide spectrum. Since this weekend I own a 4N cobalt-rod. It is a precise cylinder of 29.96 mm diameter and 32.00 mm height. The digital/analog calibrator has a measure precision of +/- 0.01 mm. My scientific scale, a Mettler PG5002 weigthed out this piece to have 199.36 g with +/- 0.01 g tolerance. Thus I conclude that the density should be between 8.827 g/cm^3 and 8.8458 g/cm^3 at 17 °C (yes it is a bit cooler in my lab :) but I think the geometry quantities should not vary much until 20 °C (and of course the density should be a bit lower at 20 °C). Therefore I support the middle value of 8.837 g/cm^3. And IF the responsable veterans on this wikepedia think to improve the quality of the density data for the publicity, then here is the reference for the above cited 8.830 g/cm^3 value: "Taschenbuch der Physik", Editor: Prof. H. Stöcker, Verlag Harri Deutsch, 2nd edition 1994, p. 147. 109.90.192.50 (talk) 19:00, 20 February 2011 (UTC)


GA Review[edit]

This review is transcluded from Talk:Cobalt/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: CrowzRSA 17:51, 30 April 2011 (UTC)

Doin...

Units

  • The infobox has links to common units of measurement e.g. Celsius (and other temperature units), Kilogram per cubic metre, day, 100 picometres (via [1 E-10 m]) and Megasecond (via [1 E6 s]). I think removing these links will improve the signal to noise ratio in the links. Lightmouse (talk) 20:15, 6 May 2011 (UTC)
    • The element infobox has been standardised with all the element articles. It seems that it's been decided to keep the units in. :-) Lanthanum-138 (talk) 02:48, 7 May 2011 (UTC)
      • Links to common units, numbers, and normal English words are in conflict with the Manual of Style, see Wikipedia:Link#What_generally_should_not_be_linked. In fact, temperature units are given as an explicit example of what not to link. But it makes no sense to penalise this one article for a fault in the infobox that affects many articles. As far as I'm concerned GA can proceed for this article. Keep up the good work. Lightmouse (talk) 10:02, 7 May 2011 (UTC)
        • The infoboxes are normaly not part of this kind of MOS. There nobody reads the whole text and links are helpful to find the right numbers you are looking for.--Stone (talk) 19:52, 10 May 2011 (UTC)
  • Sorry for the delay on the review, I'll have comments up soon. CrowzRSA 20:21, 13 May 2011 (UTC)
  • The "Occurrences" section seems a bit redundant
    This section is part of the traditional article layout adopted WP:ELEMENTS. It tells where the element can be found, whereas "Production" describes how it is extracted. That section had wrong heading level. Fixed. Materialscientist (talk) 09:09, 16 May 2011 (UTC)
  • There is no referencing in the "Organometallic compounds" section.
    Added. B12 is described in other parts. Materialscientist (talk) 09:09, 16 May 2011 (UTC)
  • The "Halides" section needs additional references.
    It is referenced to two comprehensive books (chemistry bibles). Materialscientist (talk) 09:09, 16 May 2011 (UTC)
  • What references (NiMH) batteries also contain significant amounts of cobalt, the cobalt improves the oxidation capabilities of nickel in the battery.? CrowzRSA 23:55, 15 May 2011 (UTC)
    Copied the supporting reference. Materialscientist (talk) 09:09, 16 May 2011 (UTC)
  • Have all the comments been addressed now? Lanthanum-138 (talk) 06:46, 24 May 2011 (UTC)
  • I referenced one more thing but I believe the article can now be passed as a good article. It very well written and has a good amount of information. It meets each of the criteria so I will pass it for GA. CrowzRSA 16:32, 24 May 2011 (UTC)
  • The face-centered cubic crystal structure diagram is not given. — Preceding unsigned comment added by 60.231.25.220 (talk) 04:07, 13 October 2013 (UTC)

History[edit]

It seems the earliest established use in glass is at least 2000 BCE, as it was found in an UR III site at Eridu. See:

  • ISBN 9781575060422 p. 210
  • Garner, Harry. "An Early Piece of Glass from Eridu" Iraq Vol. 18, No. 2, Autumn, 1956 JSTOR 4199608
  • Shortland, A. J., Tite, M. S., and Ewart, I., (2006) "Ancient exploitation and use of cobalt alums from the Western Oases of Egypt", Archaeometry, 48, 153–68. doi:10.1111/j.1475-4754.2006.00248.x
  • Hall, H. R. (1930) "A season's work at Ur, al-ʻUbaid, Abu Shahrain (Eridu) and elsewhere being an unofficial account of the British museum archaeological mission to Babylonia, 1919" London:Methuen OCLC 02988097

LeadSongDog come howl! 21:16, 19 October 2011 (UTC)

In the History section, in the line, "During the 19th century, a significant part of the world's production of cobalt blue (a dye made with cobalt compounds and alumina)," the word 'dye' should be replaced with 'pigment.' Dyes dissolve in application, pigments are dispersed in application as particulate matter. Mccomstock (talk) 14:48, 15 May 2014 (UTC)

Cobalt(III) hydroxide[edit]

Under "Oxygen and chalcogen compounds" cobalt(III) hydroxide is said to have the formula CoO(OH). Is the formula wrong, or was the writer referring to cobalt oxide hydroxide? KyuubiSeal (talk) 15:27, 8 November 2011 (UTC)

Important usage[edit]

Even though the amounts of cobalt usage in hard disks seems to be small[4], I think the usage is so common that it might be worth mentioning near "High speed steel" in section Alloys. Rursus dixit. (mbork3!) 09:38, 25 February 2012 (UTC)

File:Kobalt electrolytic and 1cm3 cube.jpg to appear as POTD soon[edit]

Hello! This is a note to let the editors of this article know that File:Kobalt electrolytic and 1cm3 cube.jpg will be appearing as picture of the day on June 29, 2012. You can view and edit the POTD blurb at Template:POTD/2012-06-29. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page so Wikipedia doesn't look bad. :) Thanks! howcheng {chat} 16:46, 26 June 2012 (UTC)

Picture of the day
Cobalt

Chips of cobalt, electrolytically refined, as well as a 1 cm3 cube for comparison. Cobalt is a hard, lustrous, silver-gray metal that is found naturally only in chemically combined form. Cobalt-based blue pigments have been used since ancient times for jewelry and paints, as well as blue-colored glass.

Photo: Alchemist-hp
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