The structure of the orthorhombic modification of lazurite from the deposit of the southwestern Pamirs is determined (sp, gr. Pnaa, R-hkl = 0.068, 1460 reflections). The character of the commensurate modulations of the displacements and the replacements of all the atoms in the structure is studied. Three types of sulfur radicals that replaced chlorine atoms in the sodalite-type structure are established.
The structure of the Cr-containing 2M(1) mica is determined [Enraf-Nonius automated diffractometer, MoKalpha radiation, 937 reflections with \F\ > 3 sigma(F), R-hkl = 0.048]. The parameters of the monoclinic unit cell are a = 5.240(3), b = 9.103(2), and c = 19.93(4) Angstrom; beta = 95.59(3)degrees; V = 946(3) Angstrom(3): sp. gr. C2/c; and Z = 4. The structural motif is identical to those observed in other dioctahedral 2M(1) micas. Included into the M(2) octahedron, the chromium atom increases its dimensions and increases the b parameter of the unit cell. It is shown that the structure-modeling formulas are of limited application to the unusual chemical composition of the mica under study (high Cr content and presence of Ba and F).
The structure of the mineral batisite with high potassium content from the Malyi Murunsk massif, (Yakutia) has been refined (sp. gr. Ima2, R = 0.047). It has been established that large cations are orderly distributed over the cavities of the mixed Framework and that the Fe impurity is located in one of two Ti positions. The refined structure is compared with the structures of batisite specimens studied earlier within acentric (Ima2) and centrosymmetric (Imam) space groups.
The structure of triclinic lazurite from the Malaya-Bystraya deposit (Southern Baikal area) has been determined (sp. gr. P1, R-hkl, = 0.061,5724 reflections, 210 crystallographically nonequivalent atoms). The form of the incorporation of a sulfur atom into the structure and the character of the displacement and substitution modulations of all the structure atoms have also been determined.
