THE GEMSTONE LIBRARY
Black Ammonite
These dark, polished spiral pieces are represented in our August 2025 collection as Black Ammonite. The name describes the appearance of an ammonite fossil; it is not the name of a separate mineral species. The photographed pieces have contrasting pale lines that make their coiled forms especially striking.
From marine animal to fossil
Ammonites were extinct marine cephalopods with chambered shells. Their shell shapes and internal structures are preserved in many fossils. The species, geologic age, locality, and any polishing or surface treatment details for these particular collection pieces have not been documented here.
Distinct from ammolite
Ammolite is a gem trade name for iridescent material fashioned from certain fossil ammonite shells. The black-and-pale pattern shown here is not presented as ammolite, and the picture alone cannot establish the material filling or replacing the fossil shell.
Sources
Natural History Museum · What is an ammonite? · GIA · Ammolite: An Organic Jewel
