50 Centimes Modul of ...

The "Modul" designation here is the tell. This is not a circulation strike but a module piece — a test or presentation striking produced to demonstrate a proposed compositional alloy, almost certainly connected to the French Monnaie de Paris experiments of the early 1870s following the catastrophic silver shortages and monetary disruption of the Franco-Prussian War. Copper-aluminium alloys were seriously evaluated as substitutes during this period before France ultimately retained silver for subsidiary coinage.

The F#189 variant attribution suggests this diverges from the standard type in some recorded but unspecified way — likely alloy ratio, edge treatment, or die state specific to essay production.