Abstract
Illite as a mineral of the mica group was investigated to obtain information concerning its cathodoluminescence and infrared absorption. The study included analyses by scanning electron microscope (SEM), cathodoluminescence (CL) spectroscopy and microscopy as well as infrared (IR) spectroscopy on muscovite as a reference mineral and illite from Füzérradvány, NE Hungary. CL image of illite shows relatively bright, crystallographically controlled bands and zones in the otherwise CL-dark background. Cathodoluminescence spectrum of illite from Füzérradvány shows a broad band centered at 589 nm. Illite shows eleven FIR peaks at 94, 118, 193, 260, 334, 384, 419, 473, 505, 528, and 544 cm-1, and exhibits MIR spectral features at 538 (bending vibration of SiO44-), 1038 (stretching vibrations of SiO44-), 1664 (bending vibrations of H2O), 3481 and 3641 cm-1 (stretching vibrations of OH group). In general, illite shows low intensity in the CL image and spectrum, indicating that this mineral lacks recombination centers or electron traps for the cathodoluminescence emission. It indicates that illite was formed at high temperature. CL and IR properties of illite provide useful information on its origin and microdeformations.
