Poland, 50 Groszy, 1923 Magnetic?

Poland, 50 Groszy, 1923

This coin is easily picked up with a magnet.
Is that to be expected with a nickel coin?


https://en.numista.com/catalogue/pieces2807.html

Of course !
Nickel IS magnetic.

Yet I cannot pick up an American nickle.

Until a short while ago, I had no real contact with foreign coins, and they US were generally not attracted to a magnet. I was aware that some alloys and crystalline structures may not be attracted to the magnet, (this is true of steel and cobalt as well as nickel.)
Having pulled a bunch of foreign coins, I indeed do find that they are attracted to the magnet. I guess it is the US nickle that is the anomaly.
Thanks.

Because the American "nickel" is made from an alloy of copper and nickel which is not magnetic in layman's terms. For further information read the wikipedia article about magnetism.