Pyrite ammonites are fossilized shells of extinct marine mollusks whose original material has been replaced or coated by iron sulfide (FeS₂), more commonly known as pyrite or “fool’s gold.” This rare type of fossilization, called pyritization, gives the ammonite a striking metallic sheen ranging from pale brass to deep gold. While ordinary ammonite fossils are common worldwide, pyrite ammonites are exceptional both for their rarity and their exquisite preservation.
