Gonnardite Lee Y, Hriljac J A, Vogt T American Mineralogist 90 (2005) 247-251 Variable-temperature structural studies of tetranatrolite from Mt. Saint-Hilaire: Synchrotron X-ray powder diffraction and Rietveld analysis Sample: T = 300 C, phase I _database_code_amcsd 0003725 12.9202 12.9202 6.6950 90 90 90 I-42d atom x y z occ Uiso SiT1 0 0 0 .537 .048 AlT1 0 0 0 .463 .048 SiT2 .051 .136 .625 .537 .048 AlT2 .051 .136 .625 .463 .048 O1 .392 .25 .125 .026 O2 .126 .069 .476 .026 O3 .045 .097 .862 .026 Na .687 .25 .125 .731 .046 Ca .687 .25 .125 .237 .046 Wat4 .134 .25 .125 .046