500 Francs Louis Pasteur

Issued to mark the centenary of Pasteur's death in 1895, this coin was part of France's broader commemorative program that ran through the mid-1990s under the authority of the Monnaie de Paris. Pasteur died on September 28, 1895, at Villeneuve-l'Étang, partially paralyzed from a series of strokes that had begun in 1868 — a condition he had worked around for nearly three decades while producing some of his most consequential research.

The .920 fineness is a deliberate nod to historical French gold coinage standards rather than the modern .999 norm.