Bromides of sodium,potassium,magnesium and calcium occur in sea water (about 0.07% bromine)but the Dead Sea contains much more (5% bromine).Salt deposits (e.g.at Stassfurt) also contain these bromides.Silver bromide,AgBr,is found in South America.
In the laboratory,bromine is prepared by oxidation of bromide ion;the oxidation is carried out by mixing solid potassium bromide with mangenese oxide and distilling with concentrated sulphuric acid.