Is there a US or international standard symbol for indicating that something is magnetized? I tried Googling but couldn’t find what I was looking for.
(pdf file)
Hmm… not quite. That sign indicates that there’s a magnetic field strong enough to pose a “projectile hazard” (!). I was thinking more like a symbol that’s shorthand for “this piece of metal is magnetized”.
If I remember correctly, there are only a few (like three or four) metals that will naturally form magnets, without the assistance of an electrical current. So maybe just knowing the symbols for those metals is a good first step? You want stand-alone magnets, right, not electromagnets?
The box of floppy disks on my desk has a symbol on it to indicate that it shouldn’t be exposed to magetic fields. It’s got the standard circle and diagonal line through a line drawing of a standard u-shaped magnet with lightning bolts coming from the ends. How about that (without the circle and diagonal line of course)?
I suspect Dewey Finn’s suggestion would be the best way to actually indicate that something is magnetic these days; however, for historical interest, Symbols.com shows four (likely obsolete) symbols that were reportedly used by alchemists or early chemists: a simple square, a horizontal rectangle, a symbol that looks like a little pot or cauldron, and a rectangle with two little feet.
There’s another possibly symbol here, which is also based on the standard u-shaped magnet.
At room temperature, only the elements Iron, Nickel, and Cobalt, and alloys involving them (Alnico, for example, is aluminum, nickel, and cobalt). Gadolinium, one of the rare earth elements, has a Curie point (the temperature at which a magnetic metal loses its capacity to be magnetized) well below normal natural temperatures but not down in the cryogenic range.
I believe that any number of substances become ferromagnetic (magnetizable) at cryogenic temperatures. We’d need a physicist in here to discuss that, though.