• journal_title：European Journal of Mineralogy
• Contributor：Nikita V. Chukanov ; Igor V. Pekov ; Ramiza K. Rastsvetaeva ; Sergey M. Aksenov ; Aleksandr E. Zadov ; Konstantin V. Van ; Günter Blass ; Willi Schüller ; Bernd Ternes
• Publisher：E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers
• Date：2012-
• Format：text/html
• Language：en
• Identifier：10.1127/0935-1221/2012/0024-2174
• journal_abbrev：Eur J Mineral
• issn：0935-1221
• volume：24
• issue：1
• firstpage：181
• section：Articles

The new Mg- and F-dominant lamprophyllite-group mineral lileyite (IMA 2011-021) was found at the Löhley quarry, Üdersdorf, near Daun, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany, and named for the old name of the type locality, Liley. Associated minerals are nepheline, leucite, augite, magnetite, fluorapatite, perovskite, götzenite. Lileyite is brown, translucent; streak is white. It forms platy crystals up to 0.1 × 0.3 × 0.5 mm in size and their clusters up to 1 mm across on the walls of cavities in an alkaline basalt. Lileyite is brittle, with Mohs hardness of 3–4 and perfect cleavage on (001). D_calc is 3.776 g/cm³. The new mineral is biaxial (+), α = 1.718(5), β = 1.735(5), γ = 1.755(5), 2V (meas.) = 75(15)°, 2V (calc.) = 86°. The IR spectrum is given. The chemical composition is (EDS-mode electron microprobe, mean of 5 analyses, wt%): SiO₂ 28.05, BaO 26.39, TiO₂ 18.53, Na₂O 6.75, MgO 4.58, FeO 4.48, CaO 2.30, SrO 2.23, MnO 1.44, K₂O 1.41, Nb₂O₅ 0.95, F 3.88, –O=F₂ -1.63; total 99.36. The empirical formula based on 18 anions is: Ba_1.50Sr_0.19K_0.26Na_1.89Ca_0.36Mn_0.18Mg_0.99Fe_0.54Ti_2.01Nb_0.06Si_4.06O_16.23F_1.77. The simplified formula is: Ba₂(Na,Fe,Ca)₃MgTi₂(Si₂O₇)₂O₂F₂. The crystal structure was solved using single-crystal X-ray diffraction data (R = 0.024). Lileyite is monoclinic, space group C2/m, a = 19.905(1), b = 7.098(1), c = 5.405(1) Å, β = 96.349(5)°, V = 758.93(6) ų, Z = 2. The strongest lines of the powder diffraction pattern [d, Å (I, %) (hkl)] are: 3.749 (45) (31–1), 3.464 (76) (510, 311, 401), 3.045 (37) (51–1), 2.792 (100) (221, 511), 2.672 (54) (002, 601, 20-2), 2.624 (43) (710, 42–1). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, registration number 4106/1.