Microreflectance and ellipsometric studies on the polished surfaces of some minerals

The optical properties of a series of ore minerals are assessed using microscope photometry and ellipsometry. Results from both methods are compared and any discrepancies in the data are Interpreted within the experimental and instrumental constraints of the two techniques. The errors involved in the calculation of reflectance and the optical constants n and k are also considered. A new type of microphotometric error known as the Standard-Specimen-Reflectance-Difference-Phenomenon (SSRDP) is investigated, its possible causes are discussed and tables evaluated for its correction. The results of this study are compared with those of other workers and differences between the measurements are discussed within the context of electronic, structural and impurity ion considerations. Where possible, spectral maxima are assigned to electronic and/or excitonic transitions and ideas are advanced to rationalise some of the observed reflectance dispersions. The use of spectroscopic ellipsometry in this investigation makes it possible to assess the effects of alr-formed or other contaminant films. The influence of specimen preparation on the optical characteristics is discussed and the importance of using 'real surfaces' in order to make possible the geological and commercial application of this study is emphasised