NIR reflectance spectra of powder minerals with OH groups

Actinolite OH overtones reflectance spectrum. The absorption at 1050 nm is an indication of the presence of iron two in the structure. The other sharp peaks are OH vibrations. The peak at 1900 nm could indicate some water impurity.

The tremolite spectrum is similar to actinolite although less sharp. The peak at 1900 nm is absent.

OH groups spectra in a chlorite. At 900-1100 nm is the absorption of Fe++

This is a transmission spectrum of a muscovite plate obtained with the same spectrometer.

NIR of OH bonds in serpentine.

Talc NIR spectrum showing very sharp OH absorption bands.

Black tourmaline NIR spectrum.

Glaucophane, sodic amphibole, to be compared with tremolite.

NIR spectrum of goethite. Fe++ crystal field absorption at 900 nm.

Complete visible NIR spectrum of natrojarosite showing the Fe++ peak at 900 nm and the usual OH features at 1450 and 1800-2500 nm.