[science2000]

I've been trying to dissolve a Neodymium Iron Boron magnet, and I've been putting it in different acids and stuff and the solutions all have a very unusual smell. Any ideas what this could be? It's a kinda pungent odor. I have little knowledge about rare earths and if their solutions have a characteristic odor. This might sound like an unusual question, but I want to take precautions because I was concerned maybe there's some kind of resin or organic chemical added to the alloy, which could be harmful.

[Chrataxe]

Unless its an organic acid, what would lead you to believe it was an organic compound?  But, just keep in mind what you are using.  Nd, B, Fe, whatever acid you are using, and maybe a couple of things in the air.  

[woelen]

I also noticed this smell, when dissolving many metals (e.g. praseodymium metal, erbium metal, but also chromium metal). This is due to an impurity, present in most metals. Many metals come from phosphate ores and the refined and purified metal usually still contains some phosphorus. This phosphorus usually is present as phosphide and is formed during the arc/oven reduction of the metal ore. The last traces of phosphorous (usually only in the order of 0.01% to 0.1% of the weight) are not easily removed. When the metal is dissolved in acid, then this also dissolves, giving PH3 gas. This gas has a very typical smell and is very toxic. In the small amounts, you encountered, it is not that bad, but still, it is better to be careful not to breathe too much. The metal solutions themselves are odorless.

[science2000]

Thank you for that instructional response, woelen. I knew there was something odd in the air and it concerned me.

[pantone159]

I've thought I smelled an odor of iron solutions, particularly ferrous, I think.

I had to discard the last ferrous solution I made, so I can't check this again right now.
I smelled a ferric ammonium sulfate solution I have handy, and it didn't smell like
anything, but I have definitely noticed something with other solutions before, especially
that last ferrous solution I prepared.  (I made it from ferrous ammonium sulfate salt,
not metal, so I wouldn't expect any PH3 evolving.  There would be phosphate impurities,
I imagine, but those shouldn't smell.)

[woelen]

There is a whole difference between dissolving metals and salts of metals. Metals, dissolved in acid, very frequently give rise to formation of PH3 (phosphine), due to phosphide impurities in the metal. Metal salts usually do not have that kind of impurity.

I know what you mean with that ferric smell. This is quite typical for iron salts. I also noticed it. It is the typical iron smell. It also is present when you rub some powdered rust between your fingers and smell your fingers. Or, dip your finger in a solution of any iron salt (e.g. FeCl3, FeSO4). It does not matter whether it is iron (II) or iron (III), the same smell. I do not know what it is, it has puzzled me before.

The phosphine smell is totally different from the iron smell. The phosphine smell is kind of pungest and quite unpleasant, while the iron-smell just is typical, but not pungent or alarming.

[jdurg]

I've also noticed that copper has a particular smell.  If you handle a lot of copper metal then scratch near your nose you can smell the unique odor of Cu.  Same can be said of a strongly concentrated copper salt solution.