Optical absorption and EPR spectra of fuchsite

Chromium containing mica is called fuchsite. Fuchsite originating from the Nellore district of India containing 3.37 wt.% of chromium is used in the present study. Optical absorption and EPR studies were carried out at room temperature (RT). The optical absorption spectrum gives energies at 14925, 15070, 15715, 16400, 17730 and 21740 cm(-1), which are attributed to spin-allowed transitions for Cr(3+) in an octahedral symmetry. EPR spectra show a strong resonance with g=1.98 along with two sets of weak resonances which are attributed to two sets of chromium in the sample. The zero field splitting parameter (D) is almost zero. These spectra are due to Cr(3+) in the mineral. The NIR spectrum is due to hydroxyl ions in the sample.