10 Zlotys 700th Anniversary of Warsaw, Trial Strike

Warsaw's 700th anniversary fell in 1965, and the Mint of Poland prepared multiple trial strikes in varying compositions before settling on the final circulation issue. This copper-nickel piece is catalogued as a proof of concept rather than an approved production run — the ParM and Fischer references both classify it among pattern emissions, meaning it was struck for internal evaluation and never authorized for release.

Trial pieces from Mennica Polska in this period rarely left official hands through legitimate channels.