Crystal Structure of -Uranophane
from the Transbaikal Region and Its Relation
to the Structure of the Modification

A. V. Barinova*, R. K. Rastsvetaeva**, G. A. Sidorenko***, and I. A. Verin**

* Faculty of Geology, Moscow State University,
Leninskie gory, Moscow, 119992 Russia

e-mail: rast@ns.crys.ras.ru

** Shubnikov Institute of Crystallography, Russian Academy of Sciences,
Leninski pr. 59, Moscow, 119333 Russia

*** Fedorov All-Russia Institute of Mineral Resources (VIMS),
Staromonetny per. 29, Moscow, 109017 Russia

Received August 1, 2002

Abstract—The crystal structure of -uranophane was refined (R = 0.034, 4898 independent reflections), and
its relation to the modification was established. The modifications of uranophane differ primarily in the ori-
entation of the silicon–oxygen tetrahedra with respect to the plane of the layer formed by Si-tetrahedra and U⁶⁺-
bipyramids and also in the arrangement of calcium cations between the layers. In the structure of -uranophane,
calcium cations are bound to three oxygen atoms of uranyl groups of the adjacent U–O-polyhedra, whereas
Caatoms in the modification are bound only to two uranyl oxygen atoms. © 2003 MAIK “Nauka/Interperi-
odica”.

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