 Some chloride-containing minerals include the chlorides of sodium (halite or NaCl), potassium (sylvite or KCl), and magnesium (bischofite), hydrated MgCl2.The concentration of chloride in the blood is called serum chloride, and this concentration is regulated by the kidneys.A chloride ion is a structural component of some proteins, e.g., it is present in the amylase enzyme.