Use of the laser Raman microprobe for discrimination amongst feldspar minerals

Raman spectroscopy was used to distinguish the individual members of the two feldspar subgroups. All feldspars were found to exhibit a characteristic, intense line between 500 and 515 cm⁻¹ which is attributed to a mixed Si O Si (or Si O Al) bending/stretching mode. However, discrimination between the related members within each subgroup relies on the change in frequencies and band widths which occur in the external lattice modes and in the Si O stretching region. Spectra were recorded from single crystals and powders and demonstrate that the laser Raman microprobe can provide non-destructive and rapid identification of feldspars on the microscopic scale.