[ranchak]

I have a bunch of motorcycle wheels, cylinders and engines that I want to keep for melting down some day. My concern is I don't know if the hub of the wheel is magnesium or aluminum. I have looked for ways on the internet to tell the difference, but I haven't found one that I feel 100% comfortable with. What do you guys do?

[beone]

Check some of the casting books ( Gingery's or Ammen's). A silver nitrate solution will turn black on one or the other(unfortunantly I don't remember which).

[Harryman]

A little acid like muratic/hydrochloric will fizz like crazy on mag and not on aluminum. Clean or scratch the surface first, magnesium will also corrode in water pretty easily so it's often coated.

[ranchak]

On a different board, a member suggested using nitric acid, it will turn the magnesium dark gray. I like the idea of using muriatic acid, it's easy and cheap to buy!

[drescher3]

You can also take some filings of the metal in question and try to light it with a torch. If it sparkles, it's magnesium.

[jvw1979]

I recently got hold of an old VW beetle angine.. thought it would make some great scrap to melt down ..... DON'T DO IT!!!

It turned out to be magnesium ... what a mess!

I have pictures of the aftermath on my blog .. check it out.. It makes this horrible white powder as it burns .. really messes up a crucible.

http://jvwprojects.blogspot.com/