The good Samariumitan's Aragonite
Samarium drives the fluorescence of this aragonite/calcite.
It's more of a mix, phases of the carbonates, rather than any pure mineral.
More about this specimen on the MKA fluorescent minerals website.
A spectrum revealing the activator is available for download.
Locality: Bocchegiano Mines, Tuscanny, Italy
Source: Fluorescent Minerals Workgroup MKA.