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SUMMARY. The crystal structure of synthetic kogarkoite has been determined from X-ray data collected on an automatic diffractometer. The refinement was per-formed by a least-squares method employing anisotropic thermal parameters. The 3t57 reflections with I> 3o(1) converged to a conventional R v...
| Main Authors: | , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.608.2330 http://www.minersoc.org/pages/Archive-MM/Volume_43/43-330-753.pdf |
| Summary: | SUMMARY. The crystal structure of synthetic kogarkoite has been determined from X-ray data collected on an automatic diffractometer. The refinement was per-formed by a least-squares method employing anisotropic thermal parameters. The 3t57 reflections with I> 3o(1) converged to a conventional R value of o.033. The cell content is I2 Na3SO4F, the space-group P21/m, a = I8.o74, b = 6.958, c = I 1.443 A, fl = IO7.7 I~ Kogarkoite presents a marked trigonal subcell with c' corresponding to [Io2] of the monoclinic ell. The tri-dimensional framework can be considered built up by nine differently stacked layers of Na atoms approximately perpendicular to the c ' axis (five sheets are present in galeite, six in sulphohalite, and seven in sehairerite). The very close structural relationships between these minerals are discussed. KOGARKOITE, Na3SO4F, represents a natural phase in the system Na2SO4-NaF-NaC1. This mineral was first found by Kogarko (I96I) in the Lovozero syenites (Kola peninsula) and sub-sequently inhot-springs deposits at Mt. Princeton, Colorado (Sharp, t970). A compound correspond-ing to the mineral can be easily synthesized by evaporation of aqueous Na2SO4 and NaF solu-tions. Indeed artificial sodium fluoride sulphate was described by De Marignac (t859) and later by Wolters (r9IO) and Foote and Schairer (I93o). Pabst et al. (1963) and Pabst and Sharp (I973) reported the results of crystallographic studies, assigning kogarkoite to the monoclinic system, with a marked rhombohedral pseudo-cell. The present work on the crystal structure of kogarkoite isa further contribution tothe crystallo-chemical study of the group of multiple salts having composition ranging from Na3SO4F to Na6(SO4) 2 FC1 (sulphohalite, Sakamoto, I968). Previously |
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