Fig. 6

SEM–EDS results for no. 2 eggshell sample (cross section). a, b, c The secondary electron images, small irregularly shaped particulates can be observed. d The backscatter electronic image. e The elements content results in point analysis for d (marked on red cross). f The mapping analysis results for d. The region at bottom of the sample (high F content) is matrix, not eggshell. g The backscatter electronic image. h The elements content results in mapping analysis for g. i The mapping analysis results for g. Outside of eggshell is up