The crystal structures of the related minerals triploidite (Mn2PO4OH) and zwieselite (Fe2PO4OH) are discussed. Order-disorder of OH- and F- in these structures is discussed using the results of new crystal structure refinements, and correlation with the results of Raman spectroscopic study in the hydroxyl stretching region. Cryogenic crystal structure refinement of triploidite allowed the distinction of separate OH- and F- sites in the mineral.; A new mineral, natural AsSbO3, has been found at Tsumeb, Namibia. Its occurrence has implications on the closing stage of ore formation at this mine. The crystal structure has been solved, and shown to have long range As-O and Sb-O bonding using electron density distributions from quantum calculations.
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