TY - JOUR

T1 - Crystal chemistry and nomenclature of the lovozerite group

AU - Pekov, Igor V.

AU - Krivovichev, Sergey V.

AU - Zolotarev, Andrey A.

AU - Yakovenchuk, Viktor N.

AU - Armbruster, Thomas

AU - Pakhomovsky, Yakov A.

PY - 2009/9

Y1 - 2009/9

N2 - 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 A3B 3C2MSi6O12O6-x(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.

AB - 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 A3B 3C2MSi6O12O6-x(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.

KW - Combeite

KW - Crystal structure

KW - Cyclosilicate

KW - Imandrite

KW - Kapustinite

KW - Kazakovite

KW - Koashvite

KW - Litvinskite

KW - Lovozerite

KW - Lovozerite group

KW - Nomenclature of minerals

KW - Tisinalite

KW - Zirsinalite

UR - http://www.scopus.com/inward/record.url?scp=70449417633&partnerID=8YFLogxK

U2 - 10.1127/0935-1221/2009/0021-1957

DO - 10.1127/0935-1221/2009/0021-1957

M3 - Article

AN - SCOPUS:70449417633

VL - 21

SP - 1061

EP - 1071

JO - European Journal of Mineralogy

JF - European Journal of Mineralogy

SN - 0935-1221

IS - 5

ER -