Calling all geeks

[kengr]

Back in the late 60s a local bank was giving away key chains. Pretty ordinary with a big "gold" oval fob with the banks logo on it (It may have been Lincoln Savings & Loan).

I happened to discover something interesting about the fob. It was *para*magnetic. That is, it was attracted by magnets, but only weakly. Very strange.

Whatever the fob was made of it was solid, not plated (I used a file on one edge). It got lost many years ago but I've always wondered just *what* that alloy was.

I'm hoping one of my fellow geeks might know.

Blitzkreig!
(tanks in advance :-)

Comments

[siliconshaman]

paramagnetic materials

Aluminium is paramagnetic. Anodised aluminium can be gold in colour, early anodising produced a deep layer so a file might not have exposed the silvery aluminium underneath.

[kengr]

The magnet I had (one of those alnico "lift 100 lbs" ones) wouldn't attract the sheet aluminum I had around. It *would* attract this stuff.

also it was too dense to be aluminum.

[siliconshaman]

I suspect then it was probably a Copper/niobium alloy. Copper by itself isn't magnetic, and niobium is too reactive to oxygen, but an alloy of both is the only non-oxidising gold-coloured alloy with paramagnetic properties I can find,

Also, it's dirt cheap.

[kengr]

Cool!