Structural characterization of the borate mineral inyoite – CaB3O3(OH)5⋅4(H2O)

• We have studied the mineral Ca(H4B3O7)(OH)⋅4(H2O) or CaB3O3(OH)5⋅4(H2O).
• Using a range of techniques including XRD, SEM, EDX, TG and vibrational spectroscopy.
• Both tetrahedral and trigonal boron units are observed.
• Bands due to the isotopes of boron are observed.
• Aspects of the molecular structure of inyoite are determined.

We have studied the mineral Ca(H4B3O7)(OH)⋅4(H2O) or CaB3O3(OH)5⋅4(H2O) using electron microscopy and vibrational spectroscopy. The mineral has been characterized by a range of techniques including X-ray diffraction, thermal analysis, electron microscopy with EDX and vibrational spectroscopy. Electron microscopy shows a pure phase and the chemical analysis shows the presence of calcium only. The nominal resolution of the Raman spectrometer is of the order of 2 cm−1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. Raman and infrared bands are assigned to the stretching and bending modes of trigonal and tetrahedral boron and the stretching modes of the hydroxyl and water units. By using a combination of techniques we have characterized the borate mineral inyoite.