The composition of the coin is magnesium, since this was considered a non-strategic metal by the Germans at the time. It bears the characteristic dark gray, slightly pitted appearance of an oxidized specimen of that metal. Ghetto inmates burned many of these coins, as magnesium provides a very hot, if short-lived flame. After the war, the Polish government allegedly used the original dies to counterfeit quantities of these coins to sell as 'souvenirs'.
Surviving coins of this type are not considered particularly rare or
valuable, but they provide mute testimony to one of the most tragic
events in modern history.
The owner of the coin has contacted several Holocaust museums, with the
intention of donating it. None has shown any interest.