Photo of the azure princivalleite in reflected light: crystalline aggregates in pegmatitic vein in gneiss. Field of view ca. 12 cm × 12 cm. Sample deposited in the collections of the Natural History Museum of Milano, Italy. The image is published in an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( https://creativecommons.org/licenses/by/4.0/ ). — Photo: F. Pezzotta · CC BY-SA 4.0
Princivalleite
Princivalleite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na(Mn₂Al)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃O.
It crystallizes in the hexagonal crystal system (space group R3m). It is a member of the Tourmaline structural group.
Key properties: Mohs hardness 7; specific gravity 3.168; White streak; Vitreous luster; optically uniaxial.
IMA symbol Pva, IMA status: approved, named in 2020.
At the center of a 3 cm wide pegmatitic vein, cross cutting a lens of flaser gneiss. Likely from a B-rich and peraluminous anatectic pegmatitic melt formed in situ.
It is found associated with Oxy-schorl, muscovite, quartz, albitic plagioclase, K-feldspar, pyrite, cordierite.
The mineral was named to honor Francesco Princivalle (b. 1956), Professor of Mineralogy, Department of Mathematics and Geosciences, University of Trieste, Italy.