Raman Microprobe Mineral Identification

Abstract

Raman spectroscopy and associated imaging techniques are generally non-destructive, and can be used to identify a wide range of minerals and gemstones. Raman is a sensitive technique which requires minimal sample preparation and can be used on massive specimens from lump ore to fine powders and liquids. Since glass and water are weak Raman scatterers, spectra from minerals can be obtained from samples in air, through glass, and/or immersed in water. Examples of the application of Raman spectroscopy to minerals of importance in mineral processing are discussed. These include: detection of minerals of light elements such as carbon and fluorine; distinguishing between polymorphs such as those of iron sulfides; characterizing sulfides containing minor elements such as iron in sphalerite; and the identification of silicate, oxide, and carbonate gangue minerals. The Raman microprobe also permits Raman imaging and mapping of surfaces and inclusions. Imaging of diamond is presented as an example of this technique.