Sciencemadness Discussion Board

Osmium ring is beautiful, but is it toxic ?

Radiums Lab - 18-4-2025 at 08:32

Hi guys, I always wanted to buy a ring made out of osmium (I love osmium colour more than that yellow metal's colour).

On the internet I have read many posts about it and stumbled across a few people claiming that it's toxic due to the formation of osmium tetroxide at room temperature (found these posts on reddit and quora).

As far as I know, osmium metal only reacts with oxygen at very high temperatures forming osmium tetroxide but I want some clarity and confirmation about it.

A a fellow chemistry YouTube channel called Thoisoi2 made a video about it and coverd it's properties, but didn't mention the amount of the material that reacts with oxygen.

Please help me with debunking that, many people out there stopped buying osmium ring because of those posts, and I think this thread is of some importance to the internet.

You may say buy a gold one or platinum one but there is no metal with a blue tint like osmium.

[Edited on 18-4-2025 by Radiums Lab]

Radiums Lab - 18-4-2025 at 08:43

Here is a clip of one of the post made by a quora user who says it's toxic:


Screenshot_2025-04-18-22-09-23.png - 83kB

There are many posts like this on the internet.

[Edited on 18-4-2025 by Radiums Lab]

DraconicAcid - 18-4-2025 at 08:54

I still have nightmares about the stench of osmium compounds.

Radiums Lab - 18-4-2025 at 10:10

@DaronicAcid I've neither experienced nor handled Osmium or its compounds, can you please describe your experience and the compound you've handled

Lionel Spanner - 18-4-2025 at 10:38

The powder reacts with oxygen at room temperature, but the bulk solid, which has much less surface area, requires heating to 400 °C for this to happen. Given that it's one of the hardest metals in the world, the chance of forming powder from wearing it as a ring is minimal.

To my mind, the most horrific thing about it would be the price.

DraconicAcid - 18-4-2025 at 10:42

I used to work with someone who made osmium carbonyl compounds in his research. Any time he made a batch of starting material, all the clamps and other sundry equipment that he had used would reek for days, and if you accidentally picked up something that he had used, your hands would reek.

bnull - 18-4-2025 at 10:43

Quote:
As far as I know, osmium metal only reacts with oxygen at very high temperatures forming osmium tetroxide but I want some clarity and confirmation about it.

Not exactly. It forms tetroxide at room temperature, but the rate at which it happens depends on the surface area: basically, the powder stinks and the bulk solid does not.

Bretherick's lists nothing on metallic osmium except the incompatibility with chlorine, fluorine, and phosphorus. The osmium entry in Sax's Dangerous Properties says that osmium "gives off a pungent, poisonous fume of osmium tetroxide" when heated but the "metal itself is not highly toxic," which for me is the equivalent of "having an Alsatian is safe, unless you piss it off." A review on the toxic properties of osmium tetroxide (https://pmc.ncbi.nlm.nih.gov/articles/PMC1035752/) says that the metal itself is innocuous.

Unless you're sweating halogens or phosphorus (I don't think so), the solid metal is innocuous. Don't heat the metal and don't perform experiments wearing it. I wouldn't keep it in contact with my skin for prolonged periods but that's overcautious me.

DraconicAcid - 18-4-2025 at 11:51

Quote: Originally posted by bnull  

Unless you're sweating halogens or phosphorus (I don't think so), the solid metal is innocuous. Don't heat the metal and don't perform experiments wearing it. I wouldn't keep it in contact with my skin for prolonged periods but that's overcautious me.


Copper wire stays nice and shiny on the counter, but if you wrap it around your finger, it will leave a green stain. I wouldn't trust osmium on my skin.

Radiums Lab - 18-4-2025 at 12:33

@DraconicAcid I Totally agree that you want to emphasize the toxicity of osmium but comparing a noble metal with a fairly reactive is not a good thing.

I agree that osmium tetroxide is formed when exposed to high temperatures, but still not getting why noble metals (finely divided) like Osmium would react with Oxygen at room temperature it doesn't make sense. People find osmium(while mining) in Crystal state or granular state but they never complained about dealing with chlorine like smell.

I know that osmium's concentration is too low in earths crust but there are places where you can find a lot of osmium crystals, places like meteorite impact zones have been reported to contain a fairly high concentrations Os than ur typical soil.


[Edited on 18-4-2025 by Radiums Lab]

clearly_not_atara - 18-4-2025 at 13:45

The government doesn't let you buy fucking acetic acid these days, I am certain that if osmium rings were toxic they'd have been banned a long time ago.

Ironically I think zinc has a pretty cool color as metals go, but it's far too boring and brittle and reactive to be a ring.

bnull - 18-4-2025 at 15:46

Quote: Originally posted by Radiums Lab  
I agree that osmium tetroxide is formed when exposed to high temperatures, but still not getting why noble metals (finely divided) like Osmium would react with Oxygen at room temperature it doesn't make sense.

It makes perfect sense. You just need some basic facts to see why and how it does work (meaning thermodynamic calculations and a little visualization). The process is similar to combustion, there's no new science here.

Radiums Lab - 18-4-2025 at 19:37

@bnull thank you for pointing out that Gibbs free energy value is negative (reaction is feasible at room temperature).

Oh, since is elegant indeed.

Here are some conclusions.

- Osmium does react with air to form OsO4, but it is too slow and happens in minimal quantity to pose any threat at all.

- Finer powder = faster reaction (larger surface area).

- No one is going to wear a ring made out of finely divided Os(try to wear one or make one if possible).

- After some digging, some researchers have told that even the powder take decades or centuries to react in noticable quantity.

- So, it is safe to say we can wear a ring made up of bulk osmium metal.

[Edited on 19-4-2025 by Radiums Lab]

Radiums Lab - 19-4-2025 at 07:05

@bnull I think you cannot compare oxygen reacting with Os as combustion. Combustion takes place at elevated temperatures with the help of a fuel.

bnull - 19-4-2025 at 09:05

Quote:
I think you cannot compare oxygen reacting with Os as combustion. Combustion takes place at elevated temperatures with the help of a fuel.

So, apart from temperature, what are the differences between the combustion of a fuel and the oxidation of osmium?

Radiums Lab - 19-4-2025 at 09:56

@bnull, yeah good question.

Please don't take anything personally.

- Combustion mainly occurs with utilising high amounts of O2 and realising simpler substances like CO2 or H2O(I agree that there is no H or C to form those compounds.)

- Combustion releases very high amounts of heat energy but Oxidation of Os doesn't do that(only small amounts of heat is released).

- Combustion is usually self sustaining but it's difficult in case of Os.

- Combustion usually takes place with an explosion or a fire but this doesn't do that.

- Combustion is a relatively quick process than Osmium's oxidation.

bnull - 19-4-2025 at 12:01

Quote:
- Combustion mainly occurs with utilising high amounts of O2 and realising simpler substances like CO2 or H2O(I agree that there is no H or C to form those compounds.)

Osmium needs twice as much oxygen than carbon.
Quote:
- Combustion releases very high amounts of heat energy but Oxidation of Os doesn't do that(only small amounts of heat is released).
- Combustion is usually self sustaining but it's difficult in case of Os.
- Combustion is a relatively quick process than Osmium's oxidation.

The energy released on the oxidation of carbon to carbon dioxide (393.51 kJ/mol) is very close to that from oxidation of osmium to osmium tetroxide (364.98 kJ/mol). For comparison, the oxidation of sulfur to sulfur dioxide releases 296.81 kJ/mol. The issue here is the reaction rate, which is very slow for osmium. Why? I'd say it is because osmium is almost 16 times heavier than carbon and osmium tetroxide weighs almost six times as much as carbon dioxide.
Quote:
- Combustion usually takes place with an explosion or a fire but this doesn't do that.

Not necessarily. There's smouldering: no flame, only a reddish light. Osmium, like iron, aluminum and a bunch of other metals, is pyrophoric when powdered. I don't know how small the grains need to burst into flames or at least smoulder (you can make an estimate by taking into account a whole lot of things).

I remember someone asked about how carbon actually burned, with those high melting and boiling points and what-not.

Edit: The Chemical Properties of Osmium from Mellor's Comprehensive Treatise, volume 15 (also in the Library); not up-to-date (it is from 1936) but still valuable.

[Edited on 19-4-2025 by bnull]

Radiums Lab - 19-4-2025 at 12:33

@bnull I noticed that you are online and was waiting for you to reply here.

Anyways back to the topic, ok I agree the fact that there is a small difference between their oxidation (combustion) energies, and I agree with your explanation to some extent about combustion thing but why not just call it "Oxidation" just like others do?

Here is a link to a video about Os sponge(finely divided one):
https://m.youtube.com/watch?v=AdX-T2Vv68Y&pp=ygUWT3NtaXV...

So what I understood is Os
sponge reacts easily with air forming it's tetroxide.

Osmium ring is safe to wear. Unless you are working with very high temperatures.

@bnull apology for some wrong comments about the combustion thing.

Radiums Lab - 19-4-2025 at 12:48

And guys any more suggestions for the final conclusion so that this topic can be closed or a final overview before this thread goes dead?

woelen - 20-4-2025 at 10:52

I personally also am quite sure that wearing an osmium ring is safe.
The only possible reason of not being safe for specific persons could be that people react allergically to trace amounts of osmium compounds.

Another example is nickel. Nickel is used quite a lot, for coins, but also for cutlery. It remains nice and shiny and can be cleaned well. At the same time, nickel(II) salts are known to be quite toxic and carcinogenic. But the amount of nickel(II), produced from bulk nickel metal is so small, that this risk is nearly 0. Only if you are allergic to nickel, it can cause issues. Allergic reactions can be triggered by very very small amounts.

So, I am sure that a similar thing is the case with osmium. If you have the bulk metal, and are not allergic to it, it is safe.

Cost most likely is prohibitive, but that is another matter.

Sulaiman - 21-4-2025 at 03:55

GUESSING :
if the ring is sintered rather than molten it may be quite porous to atmospheric oxygen?

stuff that comes out of my skin is surprisingly corrosive and I'm sure it is a complex mix of substances.
So corrosion on the finger may be much faster than in air, water brine etc.

Watch for colour changes that would indicate oxidation etc.

Usually our bodies give a local reaction to toxins so I guess you could wear it until any negative symptoms are noticed,
or people tend to stay upwind of you ;)

Radiums Lab - 25-4-2025 at 06:41

Ok people after a bit of digging and weeks long research here's final conclusion for this thread :

- Osmium powder and Osmium sponge react with oxygen even at room temperature to form a compound which smells like chlorine and is highly dangerous to the lungs and can even blind you. The compound formed is Osmium tetroxide (Chemical formula : OsO4).

- Osmium metal as a bulk substance, (It should not be sinter but should be melted before casting) reacts very slowly with air but the quantity of OsO4 formed is almost negligible and doesn't cause any harm.

- Always buy Osmium rings from trusted suppliers rather than local ones, because they might not have the equipment to melt cast Osmium rather they would sinter it.

- Some people's skin might be allergic to even very small quantities of OsO4 so check it out. If you have purchased it and find that you are allergic to it, gift it to someone but always remember it is a good showpiece or you have the third option , return it to the seller

- Never wear a loose Osmium ring while cooking because even though the bulk metal reacts with air very slowly, the flame or the temperature is enough to make the reaction go very quick and you'll end up producing lots of OsO4.

- Never take an Osmium ring to your local jweller to get it fixed because they won't have the equipment to get the Osmium melting instead they end up producing lots of OsO4 which is the grave digger for you.

My special thanks to these amazing people of science madness community for helping me to complete this thread :

~ DraconicAcid, ~ Lionel Spanner, ~ bnull, ~ clearly_not_atara, ~ woelen, ~ Sulaiman.

Here are very useful links :

# https://m.youtube.com/watch?v=AdX-T2Vv68Y&pp=ygUWT3NtaXV...

# https://m.youtube.com/watch?v=fe6SjQRzxZQ&pp=ygUWT3NtaXV...

• https://www.sciencemadness.org/smwiki/index.php/Osmium

• https://www.sciencemadness.org/smwiki/index.php/Osmium_tetro...


[Edited on 25-4-2025 by Radiums Lab]

zed - 12-8-2025 at 18:23

Ummm. Atara, I don't know where you are, but clearly you are not in the USA. Here, I can buy acetic acid easily. True, the price may be offensive, but availability itself is unencumbered.

https://www.ebay.com/itm/154811742295?_skw=glacial+acetic+ac...