This is a nice example of a rarely seen form of phosphorite. This phosphorus mineral takes the form of tiny black pebbles with a smooth, shiny texture. The pebbles are found as inclusions in the fossiliferous limestone matrix material that is attached to one side of this Miocene-era fossil shell. The shell is from an unidentified species and was found in the Bone Valley Formation of south Florida in Miocene-era deposits. This is a fine example of a mineral thumbnail that is also a fossil.
Refer to the photo. The black centimeter cube is shown for scale and is not included. You are purchasing the specimen shown. Your purchase will include a labeled gemjar for safe storage.