CHARACTERIZATION OF INDIAN NATURAL MINERAL ANDALUSITE USING XRD, OPTICAL ABSORPTION, INFRARED, EPR AND NMR SPECTROSCOPIC TECHNIQUES

G Anbalagan, V Sangeetha
unpublished
Andalusite, a variety of aluminosilicate mineral has been investigated through optical absorption and EPR studies. The morphology of the sample shows dense, homogeneous single-crystal structure. Prominent X-ray powder diffraction lines observed at the d-spacing 4.5255, 3.9339, 2.7898, 2.2969 and 1.2834Å confirm the crystalline nature of andalusite. Andalusite shows prominent characteristic infrared absorption bands in the region 1200-900, 900-630 and 600-450 cm-1 corresponding to Si-O. The
more » ... rum shows a broad band near 3443 cm-1 which is due to H-O-H vibrations of adsorbed water. The optical absorption spectrum attests the presence of Fe 3+ in the sample. The strong signals at g = 4.45 and at g = 5.17 are interpreted in terms of Fe 3+ at two different environments. The other EPR signal at g = 2.14 suggest the existence of Fe 3+ ion clusters. The NIR spectrum shows the presence of hydroxyl ions in the sample. 29 Si spectrum with 29 Si line at −80.052 ppm assigned to the Q 1 silicate unit. 27 Al spectrum with 27 Al line at 14.626 p.m. related to fivefold coordinated and octahedral aluminium sites.
fatcat:4xtqfdnwr5ehfihf2isag3vyte