White crystals of the very rare mineral fabriesite associated to trinepheline and jadeite from Myanmar (Tawmaw, Hpakant Township, Mohnyin District, Kachin State, Myanmar). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Fabrièsite
Fabrièsite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₃Al₃Si₃O₁₂·2H₂O.
It crystallizes in the orthorhombic crystal system (space group Pna2_1).
Key properties: Mohs hardness 5–5.5; specific gravity 2.386; White streak; Vitreous to greasy luster; optically biaxial.
IMA symbol Fab, IMA status: approved, named in 2012.
Found in serpentinized peridotite and related to the hydration of trinepheline during the late stage of metamorphism along veins in a jadeite deposit.
It is found associated with Nepheline, trinepheline, more rarely with albite, banalsite, stronalsite.
The mineral was named to honor Jacques Fabriés (1932-2000), professor of Mineralogy, National Natural History Museum, Paris, France, where he served as chair of Mineralogy from 1969 until 1998.