Linked from
The 5 pages that link to Carnallite, each with the reason it gives.
MagnesiumBroader topic: It occurs in evaporite deposits and can supply magnesium compounds.
PotashRelated: It provides potassium in ores that require separation from magnesium salts.
SylviteRelated: It commonly accompanies sylvite in potassium-rich evaporites.
Halide mineralBroader topic: Carnallite records advanced concentration of potassium-rich brines.