10 Zlotys 25th Anniversary of Polish Army, Trial Strike

Poland's communist-era mint produced trial strikes — próby — as a matter of institutional routine, submitting candidate compositions and finishes to state authorities before approving final production runs. This nickel próba for the 1968 army anniversary issue was almost certainly evaluated against the aluminum-bronze and copper-nickel variants also known for this type, with the final circulating coin struck in copper-nickel. Nickel trials of this period rarely advanced to circulation; the metal's cost and striking difficulty made it a test medium rather than a practical one.

Fischer and Parchimowicz catalog these próby separately by composition, reflecting how systematically the mint documented its own experimental output.