Raman and infrared spectroscopic studies of phurcalite from Red Canyon, Utah, USA – Implications for the molecular structure

• Raman and infrared spectra of the uranyl mineral phurcalite Ca2(UO2)3O2(PO4)2⋅7H2O.
• From Red Canyon, Utah, USA.
• Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (PO4)3− units.
• Hydrogen bond lengths were inferred from observed stretching vibrations.
• Structurally nonequivalent U6+ and P5+ was inferred from the number of corresponding stretching bands.

Raman and infrared spectra of the uranyl mineral phurcalite, Ca2(UO2)3O2(PO4)2⋅7H2O, from Red Canyon, Utah, USA, were studied and tentatively interpreted. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (PO4)3− units and to the stretching and bending vibrations and libration modes of water molecules. Approximate lengths of U–O in (UO2)2+ and O–H⋯O hydrogen bond lengths were inferred from observed stretching vibrations. The presence of structurally nonequivalent U6+ and P5+ was inferred from the number of corresponding stretching bands of (UO2)2+ and (PO4)3− units observed in the Raman and infrared spectra.

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