The crystal structure of kukisvumite, a rare mineral from Kola peninsula, Russia, has been refined in the Pccn space group with X-ray single-crystal data to R = 0.055. Kukisvumite, ideally Na6ZnTi4(Si2O6)4O4·4 H2O, has a = 29.029(4) Å, b = 8.595(1) Å, c = 5.209(1) Å, and Z = 2. Its crystal structure is closely related to that of lintisite; the latter mineral is obtained from kukisvumite through the substitution Zn2+ + vacancy = 2 Li+. In the Pccn space group an average structural model is realized, resulting in columns of half-occupied [ZnO4] tetrahedra and in zig-zag chains of half-occupied Na-centered octahedra. The actual structure of kukisvumite would imply a concerted ordering of zinc and sodium in neighbour cells. The polysomatic relationships of kukisvumite with the minerals of the lintisite family are shortly outlined.
The crystal structure of kukisvumite, Na6ZnTi4(Si2O6)4O4·4H2O
MERLINO, STEFANO;PASERO, MARCO;
2000-01-01
Abstract
The crystal structure of kukisvumite, a rare mineral from Kola peninsula, Russia, has been refined in the Pccn space group with X-ray single-crystal data to R = 0.055. Kukisvumite, ideally Na6ZnTi4(Si2O6)4O4·4 H2O, has a = 29.029(4) Å, b = 8.595(1) Å, c = 5.209(1) Å, and Z = 2. Its crystal structure is closely related to that of lintisite; the latter mineral is obtained from kukisvumite through the substitution Zn2+ + vacancy = 2 Li+. In the Pccn space group an average structural model is realized, resulting in columns of half-occupied [ZnO4] tetrahedra and in zig-zag chains of half-occupied Na-centered octahedra. The actual structure of kukisvumite would imply a concerted ordering of zinc and sodium in neighbour cells. The polysomatic relationships of kukisvumite with the minerals of the lintisite family are shortly outlined.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
