Ellenbergerite Locality: Case Parigi (Case Paris), Martiniana Po, Po Valley, Dora Maira Massif, Cuneo Province, Piedmont, Italy Field of view 7 mm. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Ellenbergerite
Ellenbergerite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mg₆(Mg,Ti,Zr, )₂(Al,Mg)₆Si₈O₂₈(OH)₁₀.
It crystallizes in the hexagonal crystal system (space group P6_3). It is a member of the Ellenbergerite structural group.
Key properties: Mohs hardness 6.5; specific gravity 3.15–3.22; Vitreous luster; optically uniaxial.
IMA symbol Ell, IMA status: approved, named in 1984.
Occurs as inclusions in pyrope porphyroblasts developed during high-pressure (25–30 kbar), medium-temperature (700 ± C{800 ± C) metamorphism of continental crustal rocks.
It is found associated with Pyrope, kyanite, talc, clinochlore, rutile, zircon, sodic amphibole.
The mineral was named to honor Professor Fran»cois Ellenberger, Paris, France, for his geological work in the western Alps.