🌎 Source: Spring Creek, Alden, Erie County, New York, 2005📏 Size: 18.5mm x 22.4mm x 18.8mm⚖️ Weight: 15g A Pyrite pseudomorph after Pelecypod specimen from New York refers to an ancient clam-like marine bivalve whose original organic shell was entirely replaced molecule-by-molecule by iron pyrite. These specific specimens originate from the famous Alden Pyrite Bed (part of the Middle Devonian Ledyard Shale Formation) exposed along Spring Creek in Alden, Erie County, New York. Specimen Breakdown The Process (Pseudomorphism): Over millions of years, anaerobic bacteria in the iron-rich Devonian mud produced hydrogen sulfide. This gas reacted with dissolved iron, triggering fluid replacement. The original shell dissolved away, while bright, metallic gold pyrite filled the exact mold—leaving a "false form" (pseudomorph) that preserves the clam's fine growth lines. Fossil Identity: In the Alden deposits, the most common pelecypods (bivalves) undergoing this golden transformation belong to the ancient genera Nuculites (like Nuculites triqueter) or Nuculoidea Physical Appearance It typically presents as a small, heavy, spherical or oval nodule. One side or the interior reveals a One side or the interior reveals a perfectly cast, brassy-gold metallic clam shell protruding from the matrix.
