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The Practical Risks of Gallium: Toxicity, Corrosion, etc...

Published 2021-6-26

Gallium is a metal that, like Mercury, is liquid at room temperature. Or rather, it might be solid, but melts in your hand. It's also the Ga in GaN, the new type of semiconductor used in the new MacBook (and other USB-C) chargers.

It's fun to play with but, before you do there's a few things you should know.

In short:

  • Remove jewelery before handling
  • Keep out of contact with other metals, especially Gold, Aluminum, Iron... and everything else
  • Keep out of open wounds
  • Once melted, it'll stay liquid at room temperature... indefinitely

Toxicity

Toxicity is not a question of if so much as a question of when (or how much).

All things are toxic to some degree - even water (particularly pure or distilled water).

As a pure element Gallium is not toxic in the same way that rocks in your yard are not toxic - though the hydrochloric acid in your stomach will cause it to form gallium chloride, so it's maybe be slightly more toxic than most rocks in your yard.

In any case, eating it might give you a stomach ache, and eating a lot could kill you, but - as mentioned above - drinking too much water can kill you too.

It's not the sort of thing that you so much as have to worry about washing your hands after handling before eating, or calling poison control if your 2-year old swallows a pea-sized amount - though for a 2-year old, a full 50g vial might be another story.

If you do put it in your mouth, you'll have a foul taste for an hour or two.

Also, much like Sodium + Chlorine (table salt) is non-toxic (and, in fact, essential to life), but Ammonia + Chlorine (windex + bleach = chloramine) is deadly, Gallium itself is non-toxic, but some Gallium by-products - such as Gallium Halides - are deadly.

Also, be sure that where blood comes out, Gallium doesn't go in. It can cause necrotic tissue damage. Again, generally not a big deal - just don't go holding it in the hand you're nursing from a knife wound, or bathing in a vat of it.

In short:

  • Don't take Gallium intravenously
  • Don't focefully consume Gallium in great quantities
  • Don't mix Gallium with random stuff in your chemistry sett
  • Don't put it on open wounds

However...

Corrosion & Alloys

This is where Gallium is dangerous.

Gallium will "amalg" with other metals at room temperature. That is to say that it will seep into them and create new (typically much worse) alloys.

Basically, it's like a metal virus - a little goes a long way, and keeps going.

Put just a little gallium on an aluminium lock, chair, or equipment stand, and a few hours later you'll have brittle, discololred, patches of metal that can no longer function as load bearing supports. Donezo.

In particular, you do not want Gallium to touch

  • Aluminium (Al Ga is a useless alloy, basically completely destroys the aluminium)
  • Gold
  • Iron (Galfenol)
  • Tin (+ Indium makes Galinstan)
  • anything that looks like metal

Again, do not put Gallium in contact with

  • Metal Sinks, Pipes, Plumbing
  • Metal Fillings / Dental Work
  • Metal Jewelery
  • Silverware
  • Anything under the hood of your car
  • Electronics (duh)
  • Microwave (duh)

In short:

  • Take off jewelery before handling
  • Don't spill into your laptop
  • Don't wash more Gallium down the sink than what goes down washing the dark gallium-rust stains from your hands and fingers

Fun Things to Do

One of the neat things about Gallium is that it seems to take a fair amount of energy to transition between solid and liquid state.

If you get it up to melting temperature (29.8˚C / 85.6˚F), it'll stay liquid even when left in a room around 75˚F overnight.

Likewise, if you put it in the freezer for 20 minutes and then bring it out, it'll take a while before it melts in your hand.

  • Put a little gallium in an empty aluminium soda can and come back an hour later... hehehe...
    • (and then add water to get the gallium back)
  • Melts in your hand (and stains your skin, but mostly washes off)
  • Melts in your mouth (and tastes foul for hours!)
  • Melts in a bowl of warm water
  • Solidifies on ice

Some tips:

  • Use ceramic bowls or plates, or plastic bags
  • Only use plastic containers for storage (eats metal, may break glass when expanding as a solid)
  • Put in the freezer for a few minutes to turn solid again (probably won't re-solidify at room temperature)

By AJ ONeal

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