Both infrared absorption and emission spectroscopy have been used to assign the vibrational bands of brucite. IR absorption bands are observed in the hydroxyl stretching region at 3698 and 3248 cm - 1 . Low frequency bands are observed at 627, 565 and 440 cm - 1 . Naturally occurring brucites are contaminated with other magnesium minerals which are easily identified by the infrared spectra. Infrared emission bands are observed at 3686, 3571, 3251 and 2940 cm - 1 . The intensity of these bands decreases upon thermal treatment corresponding to the dehydration and dehydroxylation of the brucite. Low frequency infrared emission bands are observed at 876, 706, 622 and 559 cm - 1 . Dehydroxylation of the brucite may be followed by the loss of intensity of the hydroxyl vibrations during thermal treatment. Importantly infrared emission spectroscopy enables the study of the dehydroxylation in situ at the elevated temperatures. Infrared emission also confirms the absorption bands assigned to brucite.