Many names of the chemical elements are monotonous. Some have a system imposed on them, such as the halogens, which all end in “-ine”, and the noble gases excluding helium, which all end in “-on”, but other elements also have that ending such as boron and silicon. Oxygen, hydrogen and nitrogen seem to have the start of a system, but it turned out to be flawed with oxygen, which is so named because it was thought to be responsible for acidity, Greek οξυς, but that turned out not to be so.
Element names with no classical component were usually discovered a long time ago because they are both easily observed and occur in their pure form, such as gold or silver, or because they’re easily extracted, often by heating with carbon. Hence there’s iron, copper, zinc, tin and lead, and among the non-metallic elements carbon and sulphur. Further afield, there are some elements with names derived from German or Swedish, such as nickel, bismuth and cobalt, and of course it’s this last which I’m going to talk about today.
Around five centuries ago, miners in present-day Germany came across an ore which appeared to contain a metal. However, it wasn’t possible to smelt it by the usual means and when they attempted to do so it gave off toxic fumes which killed a lot of the people doing it. Consequently they named it after their word for “goblin”: Kobold. “Goblin” isn’t an exact translation due to differences between English- and German-speaking folklore, but it’s more or less right. The next element in the row, nickel, has a name with a similar history, being a shortened version of “Kupfernickel”, “the devil’s copper”, because its ore failed to yield copper. Nickel as in “Old Nick”.
Being an odd-numbered element, 27, Cobalt is rarer than its even-numbered neighbours, particularly iron. It’s only the thirty-third most abundant element in Earth’s crust, and there are no common minerals which are specifically high in cobalt, so in a way it’s surprising it was sort of discovered so long ago and therefore isn’t one of the “-ums” or “iums”. It has the peculiar feature of being both highly toxic and essential to life, although it’s by no means unique in that way. For animals, cobalt is an essential element, but only as part of vitamin B12 or cyanocobalamin, a compound quite similar to the hæm of hæmoglobin fame but with a cobalt atom at the centre of the molecular ring rather than an iron one. Because I’m vegan and didn’t carefully watch my diet in the late 1980s CE, I have experienced B12 deficiency, which tends to manifested differently if you follow a plant-based diet. Folic acid tends to be high in such diets. Being named after the Latin word “folia” for “leaf”, folic acid is high in green vegetables and is involved in DNA synthesis, and therefore tends to mask the anæmia caused by the other deficiency, meaning that for people who don’t eat animal products the neurological features are more prominent or can even become fatal before there are any signs of anæmia. I found I got paræsthesia along the medial sides of my hands, which I did not get when I had previously had iron-deficiency anæmia fifteen years earlier (long before I was even vegetarian), I felt depersonalised, found my memory was impaired and had mild signs of Lewy Body dementia in that I mixed up dreams and waking life. I also hallucinated the smell of mint constantly and had no actual sense of smell, accidentally set fire to the bed due to that (couldn’t smell the smoke) and made some poor life decisions, which may not have been connected. Cyanocobalamin maintains the health of the myelin sheaths in the nervous system. I would say the psychosis resulting from its deficiency is more like ethanol-related psychosis than anything like schizophrenia or paranoia, and in fact I’d say it was closer to dementia than psychosis. I have not experienced the problem recently in spite of being vegan for quite some time, but I suspect I don’t absorb the vitamin as well as some other people due to my gastric lining being impaired in some way. It should also be noted that most cases of the deficiency have nothing to do with veganism, being related to malabsorption or the presence of intestinal parasites consuming the host’s food. No animals are known to produce their own cyanocobalamin, it being produced by bacteria. Its most prominent rôle in the human body is in red blood corpuscle synthesis. I won’t dwell on this too much because, as is so often the case, it belongs on one of my dormant blogs. I’m just saying that as a vegan who may have a less-than-ideal stomach lining, I’m acutely aware of the function cobalt has in my body from a practical perspective.
It’s also toxic. Although it’s unusual to be poisoned by cobalt in the usual run of events, some hip implants contain it and this is a significant cause. It can lead to mood swings, rashes, PTSD-like symptoms, problems with vision and tinnitus. If it comes in contact with the skin for protracted periods, it can cause a rash, and if particles of it are inhaled it can lead to pulmonary fibrosis and lung damage. Most of the last two routes describe a fairly common kind of reaction. Swallowing it will lead to nausea and vomiting, which is the elimination reaction to things which are not meant to enter the internal environment but still can, and because of this reaction cobalt poisoning by ingestion is often self-limiting. The same does not apply to implants such as hip replacements, which can’t be eliminated by the body and will therefore continue to provoke reactions and cause direct problems.
The metal is probably best known in the form of one of its compounds, cobalt blue. This is actually cobalt (II) aluminate, and is shown at the top of the post. As I mentioned yesterday, I don’t understand colour physics or chemistry but I’m aware that like some other transition metals, cobalt can form ions at different oxidation states and this influences the colour. The fact that this happens with chromium is the reason for its name – χρομα – colour. Consequently some cobalt compounds are a rich blue and others are purple or pink. Cobalt glass is of course blue:
As has been done here, herbal and essential oil bottles for use in dispensing are sometimes blue because blue is said to be a healing colour. In practical terms it may make sense to give patients blue glassware because it will be more likely to be returned rather than recycled, but all the glass bottles I’ve used have been brown. Cobalt glass is made by adding a cobalt compound to softened glass, nowadays often an oxide of cobalt or cobalt (II) carbonate, which tells you which oxidation state is blue, although older glassware would’ve used cobalt aluminate, which is quite ancient and was also used in pottery. Cobalt blue is the pigment our pottery teacher warned us about at school and explained why food and drink were banned in his classes, and was used in Tang dynasty glazes in Chinese ceramics. Its toxicity is not relevant when used in glass or finished ceramics, but it’s still interesting that blue is often seen as the antithesis of edibility, as in “there are no blue foods” (in fact there are, but they’re rare). This is also hard to reconcile with the idea that blue is a healing colour. The forger of Jan van Vermeer paintings van Megeren used cobalt blue paint in some of his reproductions, which enables those to be detected as fake.
Incidentally, a quite remarkably blue pigment was discovered about a dozen years ago consisting of yttrium, indium and manganese:
Apart from also being composed of transition metals, this has little to do with cobalt but it’s worth a mention.
Cobalt is a useful catalyst, which in fact is how living things use it in cyanocobalamin. The not very nice sounding cobalt arsenide accelerates the electrolysis of water and becomes more efficient as it ages, making it useful in the production of hydrogen as fuel. This increase in efficiency is due to it becoming more porous as it goes on, increasing its surface area for reactions. It can also be used to convert syngas to liquid automotive fuel.
Cobalt chloride is quite interesting. It changes from purple or pink to blue depending on hydration. Cobalt atoms can bond by electrostatic attraction, meaning that they can link to up to six water molecules at once. Without water, cobalt (II) chloride is blue:
When hydrated, it looks like this:
This is the hexahydrate – six molecules of water per cobalt ion. Cobalt chloride paper is used to check for humidity and moisture because of this colour change. The compound is also one of several chemicals which can be used to make a chemical garden, although with copper sulphate, hydrous and anhydrous, and alum. These can be “planted” in a bath of aqueous sodium silicate, when they will proceed to sprout long projections:
This works because the silicates of the metals involved are less soluble than the original compounds. Unfortunately it’s hard to imagine circumstances where this could happen without intelligent intervention.
A very sinister and unpleasant aspect of cobalt is the cobalt-salted nuclear weapon, conceived of in 1947 by Leo Szilard. It’s called “salted” because it resembles the ancient practice of salting the land by an enemy to prevent the production of food and cause famine. The idea was to surround a nuclear fusion weapon with a shell of cobalt which, when detonated, would spread cobalt-60 (having previously been cobalt-59 but hit by neutrons from the chain reaction) around a wide area, which has a long half-life and is a strong gamma ray emitter, gamma radiation being the most penetrative form of radioactivity from nuclear decay. This was to show that there was an apocalyptic risk from nuclear weapons, but it was not suggested that such a weapon would be built, merely that the technology being “out there” was an existential hazard. As far as is publicly-known, this has never been done. Salted bombs are kind of similar to dirty bombs but the fallout would be scattered over a much wider area, which would be uninhabitable for more than half a century afterwards. A small number of such bombs could wipe out the human race. The point was not that they actually be developed but to encourage nuclear disarmament, although there are rumours and leaks of something similar such as an underwater bomb to produce a radioactive tsunami.
Cobalt is also used in powerful magnets, although this function is largely superceded by rare-earth magnets now. The most powerful magnet of all, though, seems to be samarium-cobalt, whose other component is a rare earth element. I don’t understand magnetism in detail either, but I do know that apart from iron, only cobalt and nickel are ferromagnetic among the transition metals although several rare earth metals also are. Cobalt-samarium magnets retain their ferromagnetism at higher temperatures than other magnets with rare earth elements and are used in guitar pickups.
To close this off, this post was written in response to an AI program which suggested this title for a blog post among a list of about twenty others, all of which were for recipes. I have no idea why it was there but I hope it made for an interesting post. And this is cobalt:
A Box Of Chocolates 