Pezzottaite was renamed to pezzottaite-(Cs) in September 2025, according to the official IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) newsletter.
Why: The renaming was part of a comprehensive nomenclature scheme established for the newly formalized beryl supergroup. The general formula for all minerals in the beryl supergroup is ABT13M2(T26O18), and suffixes were systematically established for the constituents of the A and B sites to clarify the distinctive elemental composition of each mineral.
Since pezzottaite's defining characteristic is its cesium (Cs) content in the A-site of its crystal structure—with the ideal formula Cs(Be2Li)Al2(Si6O18)—the addition of the "(Cs)" suffix explicitly denotes this compositional feature. This naming convention distinguishes it from other beryl group members and follows the same standardized approach applied to similar minerals like johnkoivulaite, which was simultaneously renamed to johnkoivulaite-(Cs) for the same reason.
The beryl supergroup classification, which included these nomenclature changes, encompasses two main groups: the beryl group (containing beryl, bazzite, stoppaniite, pezzottaite-(Cs), and johnkoivulaite-(Cs)) and the cordierite group.
