Pentaborate Polyanion in the Crystal Structure of Ulexite, NaCaB5O6(OH)6·5H2O

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Science  18 Sep 1964:
Vol. 145, Issue 3638, pp. 1295-1296
DOI: 10.1126/science.145.3638.1295


Triclinic ulexite crystals contain isolated borate polyanions [B5O6(OH)6]3- related to the well known pentaborate polyanion [B5O6(OH)4]- by addition of two hydroxyl groups to two opposite B-O triangles. The isolated ulexite polyanions form the [B5O7(OH)4]n3n- chains previously found in crystals of the related mineral probertite, NaCaB5O7(OH)4·3H2O.