So, unfortunately it seems to have failed the magnet test. (Had to check what fail and pass were for that lol)

Interestingly though, the lid of it is magnetic. And I was only using what I had at my friend's house, which were small basic fridge magnets.

I read it's maybe possible it's still not aluminum just because it didn't stick to a magnet? I've got some stronger magnets at home but it will be a few days still before I can test that.

And I couldn't find anything which was pure copper, save for finding and stripping a wire somewhere.

Thank you very much for your help here. It has been incredibly beneficial for this search.

I will continue looking for strong magnets just in case, as well as reading where I can to see if anything says what else it could be.

I may be at the end of what I can do outside of testing a sample of the material itself, but if anything comes to mind at any point, please feel free to toss it here. I'll be checking back for sure as well as updating with anything I find.

Thanks again!