• journal_title：European Journal of Mineralogy
• Contributor：Igor V. Pekov ; Sergey V. Krivovichev ; Andrey A. Zolotarev ; Viktor N. Yakovenchuk ; Thomas Armbruster ; Yakov A. Pakhomovsky
• Publisher：E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers
• Date：2009-
• Format：text/html
• Language：en
• Identifier：10.1127/0935-1221/2009/0021-1957
• journal_abbrev：Eur J Mineral
• issn：0935-1221
• volume：21
• issue：5
• firstpage：1061
• section：Articles

The paper summarizes crystal–chemical data and describes the IMA-accepted nomenclature of lovozerite-group minerals (LGM). The lovozerite group includes nine zeolite-like cyclosilicates with the general formula A₃B₃C₂MSi₆O₁₂O_6x(OH)_x·nH₂O, with species-defining M = Zr, Ti, Fe³⁺, Ca; C = Ca, Mn²⁺, Na, □; A = Na, Ca; B = Na, □;0 ≤ x ≤ 6; n = 0–1. Their structures are based upon a heteropolyhedral framework consisting of rings of Si-centred tetrahedra and M-centred octahedra forming a 3D system of channels that host A, B, and C cations. The structures can be also considered as based upon pseudocubic modules centred at the midpoint of the Si tetrahedral ring. The M, A, and B cations are located at the borders of the module, whereas C cations are inside the module. The modules are stacked in three different arrangements in LGM allowing distinction of three subgroups: (1) zirsinalite–lovozerite subgroup (includes cation-saturated combeite, kapustinite, kazakovite and zirsinalite, and cation-deficient litvinskite, lovozerite and tisinalite), (2) koashvite subgroup (incl. koashvite) and (3) imandrite subgroup (incl. imandrite). The nature of cation-deficient LGM is discussed. The calculation scheme for empirical formulae of LGM and the criteria of definition of a mineral species (end-members) in the group are given.