• journal_title：American Mineralogist
• Contributor：Hongwei Ma ; David L. Bish ; Hsiu-Wen Wang ; Steve J. Chipera
• Publisher：Mineralogical Society of America
• Date：2009-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2009.3110
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：94
• issue：4
• firstpage：622
• section：Letters

The crystal structure of sanderite, MgSO₄·2H₂O, was determined from laboratory X-ray powder diffraction data measured from 2–140 °2𝛉 using CuKα radiation. Sanderite is orthorhombic, space group P2₁2₁2₁, with unit-cell parameters a = 8.8932(1) Å, b = 8.4881(1) Å, c = 12.4401(2) Å, V = 939.16(3) ų, Z = 8. The crystal structure model was determined using the charge flipping method and was refined using fundamental parameters Rietveld refinement method to R_wp = 6.52%, R_exp = 1.89%, and χ² = 3.43. Bond-valence calculations for the refined model show that the structure is chemically reasonable. In the refined structure, Mg²⁺ cations are coordinated by four O atoms from [SO₄]²⁻ groups tetrahedra and by two H₂O molecules, forming distorted octahedra. By sharing vertex O atoms, [SO₄] and [MgO₄(H₂O)₂] octahedra build up a 3-D framework.