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Scanning Electron Microscopy applications in Earth Sciences
Author: Madelaine Frazenburg, Dr Alicia Botes & Jurgen Kriel
Published: 23/09/2020


​Many geological samples contain a variety of phases. Some of these phases are not easily distinguishable using a backscattering electron detector (BSD). In this case, Energy Dispersive X-ray analysis (EDX) and/or Wave dispersive analysis (WD) are useful to determine the varying chemical composition of the different phases. Combining the EDX or WD information with an elemental map as seen in Figure 1, can show you the location of the various phases using color overlays. This provides the chemical composition and identity of the samples and helps locate important areas and features in minor constituents.


Figure 1. BSD SEM image showing different mineral types with different textures and zonings in geological rock. 

Montage Phase Map is a digitally stitched electron image of an X-ray map where the software creates a composite area view by moving the stage in an X-Y raster while capturing snapshots from continuously running DigiScan images. This feature offers chemical spectrum/elemental maps & electron images.


Figure 2. Elemental phase mapping primarily highlights the spatial distribution of each element across the surface of a sample. The above map highlights different elements in garnet. The warm colors '(heat') highlight high concentration of an element.

Elemental phase mapping primarily highlights the spatial distribution of each element across the surface of a sample. The map highlights different elements in geological rock. The warm colors ‘(heat’) highlight high concentration of an element.​


Figure 3. Image indicating automatically searched zircon crystals.​

The CL detector provides valuable insight into the internal structure and composition of luminescent or optical materials. Useful solutions include the ceramic and mineral industry, petrochemistry, pharmaceutical industry, and biopetrology.

Figure 4. CL images showing the growth zonation for different zircon grains,100μm.

Samples that typically consist of alloys and metals are often tested for thermal, mechanical, and corrosion-resistant properties. The effects of these tests can be visualized using SEM. EDX can be used to establish the chemical composition of your samples as well as confirm, identify, and quantify the elements throughout the sample.

Figure 5. Alloy metal a) indicating different elemental zones analysed separately b) linescans indicate variation elemental concentration

Figure 6. An example of a Montage (a) with elemental map (b) with color overlay indicating Cu (green).