Here's why:

* Halides are minerals composed of a metal cation and a halogen anion.

* Halogens are elements in Group 17 of the periodic table, including fluorine (F) and chlorine (Cl).

Some common examples of halide minerals containing fluorine and chlorine:

* Fluorite (CaF2): Contains calcium and fluorine.

* Halite (NaCl): Contains sodium and chlorine (table salt).

* Sylvite (KCl): Contains potassium and chlorine.

So, minerals formed by fluorine and chlorine fall under the broader category of halide minerals.