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Licensed Unlicensed Requires Authentication Published by De Gruyter March 25, 2015

The crystal structure of gearksutite, CaAlF4(OH)· H2O

  • Fabio Marchetti EMAIL logo and Natale Perchiazzi
From the journal American Mineralogist


The discovery of unusually well-crystallized samples of gearksutite allowed determination of its crystal structure. The crystals belong to space group P1̅ , a = 4.940(1), b = 6.810(1), c = 6.978(1) Å; a = 101.12(1), β = 94.86(1), γ = 110.07(1)°; V = 213.43(6) Å3; Z = 2. The structure consists of layers of eightfold-coordinated calcium polyhedra connected through pairs of [Al2F8(OH)2] octahedra which are oriented identically, similar to those observed in other hydroxyl aluminum fluorides. A comparison with other minerals of similar composition is made. The structure data allowed us to reliably index the powder pattern and to show that the reflection intensities are strongly affected by preferred orientation.

Received: 1998-11-9
Accepted: 1999-8-11
Published Online: 2015-3-25
Published in Print: 2000-1-1

© 2015 by Walter de Gruyter Berlin/Boston

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