Auction Win: Fossilized Coral (Cast)

Locality: Clay Center, Allen Township, Ottawa County, Ohio, USA

Size: Miniature - 4.75 × 5.25 × 1.5 cm

Fossilized coral is the preserved exoskeleton of ancient marine colonies, typically composed of calcium carbonate (CaCO3) that has been replaced by silica (SiO2) to form agate or chalcedony pseudomorphs. These specimens, such as the agatized Florida coral from the Oligocene-Miocene Epochs (38–25 million years ago), are highly prized by collectors for their exact replacement of the living coral's texture and structure. A memorable fun fact is that some fossilized corals, like the Petoskey stone (Hexagonaria percarinata), display intricate hexagonal patterns visible even in black-and-white photos.

The primary source of mineral specimens from this locality is the White Rock Quarry, an active quarry for building stone and aggregate located on the north edge of Clay Center. This quarry exposes rocks from the Lockport Dolomite and Greenfield Dolomite, which have produced notable specimens including calcite, fluorite, marcasite, pyrite, and celestine. Collectors today recognize Clay Center specimens as originating almost exclusively from this long-operating quarry, which has been in production for several decades.