**2.2. The group of belovite**

The minerals from the group of belovite are cation ordered. Strontium substitutes for Ca in the M(2) site, and Na + REE substitute for Ca in the M(1) site. This results in lowering of symme‐ try from P63/M (the space group of the apatite archetype structure) to P63 (fluorstrophite, fluorcaphite), *P*3 ¯ (belovites), or P3 (deloneite) [1].
