**3.2.5. Scanning electron microscopy and WDX analysis**

The microphotographs from SEM analysis of break plane of investigated fluorapatite speci‐ men are shown in **Fig. 20**. The series of conchoidal fractures on the surface show brittle fracture as further characteristic properties of apatite.

<sup>24</sup> It was calculated as 100 × molar mass (molar weight) of CO2/molar mass of CaCO3.

<sup>25</sup> Theoretical mass loss (3.77%) of fluorapatite was used to set the fixed value of parameter A2.

**Fig. 20.** SEM image of the break plane of investigated fluorapatite specimen: 50× (a), 75× (b), 1 000× (c) and 5 000× (d).

**Fig. 21.** Typical results of WDX analysis of the fluorapatite specimen and simulation of electron–specimen interaction.


The chemical composition of sample was determined by WDX analysis (**Fig. 21**). The aver‐ age results are introduced in **Table** 3.

**Table 3.** Average chemical composition of investigated specimen of fluorapatite.

The composition of fluorapatite (Ca5(PO4)3F → Ca5P3O12F) corresponds to the element ratio: Ca:P:O:F = 5:3:12:1. The results of WDX analysis of investigated specimen (**Table** 3) are in good agreement with the composition of ideal fluorapatite and fulfill all the criteria mentioned in **Section 1.4**.
