Small colorless almost completely molten (since it is very hygroscopic) aggregates of the extremely rare mineral carobbiite, a mineral of simple chemistry since it is KF. From: Somma-Vesuvius, Naples Province, Campania, Italy. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Carobbiite
Natural potassium fluoride — a very rare, soft, colorless cubic mineral found at Mount Somma, Vesuvius.
Intro adapted from Wikipedia (CC BY-SA).
Carobbiite is an IMA-recognized mineral species in the halide class, with the chemical formula KF.
It crystallizes in the cubic crystal system (space group Fm3m). It is a member of the Rocksalt structural group.
Key properties: specific gravity 2.53.
IMA symbol Crb, grandfathered status — known before the IMA’s founding, named in 1956.
Found in stalactites in cavities in lava.
It is found associated with Halite, mercallite, hieratite.
The name refers to Professor Guido Carobbi (1900–1983), Italian geologist, Institute of Mineralogy and Geochemistry, University of Florence, Florence, Italy, who collected the first specimens.