New Data on Mineralogy and Crystal Chemistry of the Lovozerite Group: Unusual Varieties of Kazakovite and Litvinskite

Unusual chemical and structural varieties of two lovozerite-group minerals from the Lovozero alkaline complex (Kola Peninsula) were studied by means of electron microprobe analysis, single-crystal X-ray diffraction, and IR spectroscopy. The Zr-and Fe-rich variety of kazakovite with the composition Na6.20U0.01(H3O)(0.25)(Mn0.72Ca0.10)(Sigma 0.82)(Ti0.61Zr0.18)(Sigma 0.97)Si6O17.83(OH)(0.17) was found in the Palitra pegmatite body, Mt. Kedykverpakhk. The mineral is trigonal, R (3) over barm, a = 10.2622(5), c = 13.0884(7) angstrom, V = 1193.71(13) angstrom 3; R-hkl = 0.0383. The variety of trigonal litvinskite from Mt. Alluaiv is characterized by the lowest total content of large cations sum (Na, Ca, and Mn) and the space group previously unknown for this mineral R3m. Its composition is Na-2.05(H2O)(0.64)(Mn0.13Ca0.02)(Sigma 0.15)(Zr0.93Ti0.06Fe0.023+])(Sigma 1.01)Si6O12.36(OH)(5.64), and unit cell 3 parameters are: a = 10.1880(10), c = 13.1209(16) angstrom, V = 1179.4(3) angstrom 3; R-hkl = 0.0665. The presence of hydronium H3O+ was first revealed for lovozerite-group minerals. The possibility of formation of kapustinite and litvinskite as a result of the step-by-step townendite alteration process (decationization with the replacing of the corresponding part of O2- by OH-) is discussed.

Automated summary

Chemical and structural variations of two lovozerite-group minerals from the Lovozero alkaline complex on the Kola Peninsula were studied using electron microprobe analysis, single-crystal X-ray diffraction, and IR spectroscopy. The presence of hydronium H3O+ was revealed for the first time in lovozerite-group minerals. The formation process of certain minerals was discussed.