Halogens 6.1 6.1 Sources of Halogens
Fluorine - Sources include the minerals fluorspar and cryolite.
Obtained by electrolysing potassium hydrogen chloride in anhydrous HF and in an inert vessel.

Chlorine - Sources include NaCl, canallite and sylvine.
Obtained by electrolysis of NaCl in a diaphragm cell.

Bromine - One source is sea water (but low ppm so not viable).
Alternative source is from brine deposits

Iodine - It is in sea water, sea weeds and brines. Comercially it is obtained from brine.

Astatine - Only ever 20g on whole Earth (T_1/2 = 8 hrs).