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Figure 4: SEM/EDS images of the surface of the cross-section (4.5 × 6.0  𝜇 m) of porous silicate glass sample which was obtained after breaking the sample. The first photo shows an SEM visualization of the cross-section surface. The remaining three photos represent space distribution of different elements, Si, O, Fe, identified in this cross-section with the respective color saturation corresponding to the actual density of the identified elements.