USING REFLECTANCE SPECTROSCOPY TO ESTIMATE THE ORIENTATION OF QUARTZ CRYSTALS IN ROCKS

Quartz is an anisotropic mineral, and each mid-infrared (7-15 mu m) reflectance spectrum collected from an individual quartz crystal is strongly influenced by its orientation. As a result, quartz reflectance spectra contain features that systematically change with orientation. In this study, the trough at 8.63 mu m was used to derive crystal orientation information from quartz reflectance spectra collected using a high spatial resolution spectrometer with a 100 x 100 mu m spot size. The intensity of this trough was quantified using two band ratios (Ref(8.48) / Ref(8.63) and Ref(9.01) / Ref(8.63)), and band ratio Ref(8.48) / Ref(8.63) was used to infer the orientation of quartz crystals in an Archean granite sample to characterize any fabric.