:Locality: Löhley, Üdersdorf, Daun, Eifel, Rhineland-Palatinate, Germany Size: 1.9 × 1.4 × 1.1 cm Description: Group of tabular platy lileyite crystals, with the classical brown-yellowish colour. Lileyite is a very rare species and this specimen is from the TL. Accompanied by altered götzenite prismatic crystals. In the matrix some nepheline, pyroxene group, magnetite. Analyzed specimen. — Photo: Joan Rosell , from rosellminerals.com · CC BY-SA 4.0
Lileyite
Lileyite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ba₂Ti₂Na₂Fe²⁺Mg(Si₂O₇)₂O₂F₂.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Seidozerite-Lamprophyllite structural group.
Key properties: Mohs hardness 3–4; specific gravity 3.776; White streak; optically biaxial.
IMA symbol Lly, IMA status: approved, named in 2011.
Found in miarolitic cavities in an alkaline basalt.
It is found associated with Nepheline, leucite, augite, magnetite, fluorapatite, perovskite, götzenite.
The name refers to the old name of the first known locality, Liley, Germany.