Raman Spectra of Prehnite, Apophyllite and Inderite.

Prehnite

Prehnite sample and two Raman spectra recorded for 2 perpendicular directions. This sample is not oriented.

Prehnite low range spectrum.

The hydroxyl groups present in the Prehnite mineral can be seen on the spectra above showing two closely spaced stretching OH vibrations.

Apophyllite

Two specimens of apophyllite are shown below. The spectra where recorded on the monocrystal on the right on a pyramidal face without any preparation.

Low frequency spectrum of apophyllite. Spectra marked "parallel to c" are recorded with laser light polarization along the black arrow on the photograph above. Spectrum perpendicular to c is polarized along red arrow. The section orientation is thus not strictly parallel to the c axis.

High frequency spectrum of Apophyllite. Oh band. The narrow peak at 3560 cm^-1 arise from the stretching vibrations of hydroxyl groups in the crystal. The large multi-band structure from 2700 to 3500cm^-1 is comming from vibrations of water molecules in the mineral.

Inderite

I have found a microcrystal of Inderite, mineral formula: MgB3O3(OH)5•5(H2O).

Inderite low frequency Raman spectrum.

The presence of OH radicals and H2O molecules in the formula of Inderite gives this rich spectrum in the high frequency range. The broad H2O stretching vibrations group is rather complex probably due to hydrogen bonds giving bands at rather low frequencies.