The SEM images of synthetic and biogenic CaOx
are shown in figure 2. In relation to synthetic CaOx,
the crystals of the biogenic material are larger with
clearly defined forms, similarly to a carnation flower.
The SEM images show morphological differences
between synthetic and biogenic crystals. The biogenic
crystals were not damaged but preserved during the
extraction and concentration procedure. These results
confirm the efficiency of the extraction and
concentration process described here.