Figure 4
Correlative SEM/EDS and NLO (SRS and SHG) imaging. (a) A large area back scattered electron image of a thin section from a rare earth element bearing carbonatite ore, with the region of interest to be compared with SRS/SHG imaging outlined in red. (b) An overlay of SEM-EDS elemental analysis. Si is colored in cyan, Ca in magenta, and S in yellow. Comparing with other elemental maps allowed us to identify the cyan region as quartz, the magenta region as ankerite containing CO3, and the yellow region as barite containing SO4. (c) An SRS spectral scan with simultaneous SHG imaging, identifying several different regions. This composite image was formed by stitching together 9 fields of views before binarizing the images to identify different regions. The SHG (i.e. quartz) represented by cyan, a carbonate Raman mode centered around 1090 cm−1 (CO3) colored as magenta, and a sulfate Raman mode at 985 cm−1 (SO4) represented by yellow. It can be seen that the global spatial correlation between (b,c) is very good, confirming that SRS/SHG imaging can be used for mineralogical analysis of economic ores.
