DETERMINATION AND REFINEMENT OF THE CRYSTAL STRUCTURE OF CHAIDAMUITE

<正> Chaidamuite (ZnFe（SO4）2（OH）. 4H2O), which is a new sulphate mineral, belongs to the triclinic system, space group P1, with the cell parameters corrected by the least-squares method: a=7.309（2）, b=7.202（2）, c=9.691（3）, α=89.64（3）, β=105.89（3）, γ=91.11（2）°, Z=2. The crystal structure has been determined by the Patterson method and Fourier syntheses and refined by the full-matrix least-squares method to an R factor of 0.032, using 2833 independent reflections. In the structure, a zigzag chain consists of [Fe（1）O5（OH）] and [Fe（2）O5（OH）] octahedra sharing the OH corners, and an octahedral-tetrahedral chain running parallel to the b axis consists of the zigzag chain of Fe octahedra and （SO4） tetrahedra sharing four pairs of octahedral corners on either side of the zigzag chains. These chains are cross-linked by the isolated [Zn（1）O2（H2O）4] and [Zn（2）O2（H2O）4] octahedra into corrugated sheets parallel to the （100） plane. Adjacent sheets are hydrogenbonded through water molecules.