Vibrational spectroscopy of the mineral meyerhofferite CaB3O3(OH)5·H2O – An assessment of the molecular structure

• Meyerhofferite Ca2(H3B3O7)2·4H2O is found in sedimentary or lake-bed borate deposits.
• We have studied the Raman and infrared spectra.
• We have assessed the molecular structure of meyerhofferite.
• A comparison is made between the Raman and infrared spectrum.
• Raman spectroscopy proved far more useful for the detection of meyerhofferite than infrared spectroscopy.

Meyerhofferite is a calcium hydrated borate mineral with ideal formula: CaB3O3(OH)5·H2O and occurs as white complex acicular to crude crystals with length up to ∼4 cm, in fibrous divergent, radiating aggregates or reticulated and is often found in sedimentary or lake-bed borate deposits.The Raman spectrum of meyerhofferite is dominated by intense sharp band at 880 cm−1 assigned to the symmetric stretching mode of trigonal boron. Broad Raman bands at 1046, 1110, 1135 and 1201 cm−1 are attributed to BOH in-plane bending modes. Raman bands in the 900–1000 cm−1 spectral region are assigned to the antisymmetric stretching of tetrahedral boron. Distinct OH stretching Raman bands are observed at 3400, 3483 and 3608 cm−1. The mineral meyerhofferite has a distinct Raman spectrum which is different from the spectrum of other borate minerals, making Raman spectroscopy a very useful tool for the detection of meyerhofferite in sedimentary and lake bed deposits.

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