MINERALOGICAL MAPPING OF SCANNING ELECTRON-MICROGRAPHS

A technique is described to map regions of back-scattered scanning electron images according to the mineralogy of the specimen. Such a technique may be used to study in detail the micro-mineralogy of geological materials. In particular, the size, shape, and distribution of the individual components may be studied. Such information could provide additional evidence on the origin and nature of such materials. Composite multi-layered images are constructed from both back-scattered images and X-ray maps of the same area of relevant elements. Training areas representative of the different mineral classes present are defined, and the statistics within these areas are used to classify the whole image. Changes in classification parameters appear to have little effect on the determined composition. Segmentation of an image by this means is superior to techniques using a single image. Following segmentation, particle size parameters for the constituent mineral grains may be determined. Examples showing different size frequency distributions for the different minerals are included. Several practical points on the use of the method are also covered.