A new centrosymmetric modification of Pb-hilgardite Pb
2[B
5O
9](OH) · 0.5H
2O is synthesized hydrothermally under conditions close to natural. This modification is intermediate between the centrosymmetric
monoclinic phase studied earlier and the polar orthorhombic phase. The occupancies of the framework voids with water molecules,
OH-groups, and halogen atoms are considered for all the known varieties of hilgardite. The correlation between the conditions
of hilgardite formation and types of structure is established.
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Translated from Kristallografiya, Vol. 47, No. 3, 2002, pp. 435–438.
Original Russian Text Copyright © 2002 by Borisova, Dimitrova, Belokoneva.