[GammaBettaFluxx3000]

I recently acquired a sample of Cerium for my element collection.
It came in a plastic bag under kerosene.

I removed it from the package and washed it to remove the oil/kerosene.
The sample is now sitting in my desk in open air.

-- Can I keep it that way? Or Will it just oxidize further and further until it crumbles apart in a few months/years?

[AWK]

https://www.webelements.com/cerium/chemistry.html

[GammaBettaFluxx3000]

https://www.webelements.com/cerium/chemistry.html

Well, thanks, the link you provided only says Ce will tarnish when exposed to air. But that's all.
So my sample should be fine as long as I don't remove the layer of oxide that formed over it, right?

[chenbeier]

If possible put it in a glass tube unter nitrogen or argon.

[GammaBettaFluxx3000]

If possible put it in a glass tube unter nitrogen or argon.

Unfortunately I don't have access to any of those :/

But thanks anyway.

[Enthalpy]

Wiki: "Cerium metal is highly pyrophoric, meaning that when it is ground or scratched, the resulting shavings catch fire."

Liquid paraffin wasn't a bad idea.