Its chief commercial sources are the salt deposits at Stassfurt in Prussian Saxony, in which magnesium bromide is found associated with various chlorides, and the brines of Michigan, Ohio, Pennsylvania and West Virginia, U.S.A.; small quantities are obtained from the mother liquors of Chile saltpetre and kelp. In combination with silver it is found as the mineral bromargyrite (bromite).
The leading silver minerals are native silver; argentite or silver glance, Ag 2 S, usually containing small amounts of lead, copper and tin; dyscrasite or antimonial silver, Ag 2 Sb to Ag,3Sb, an isomorphous mixture of silver and antimony; proustite or light red silver ore, Ag 3 AsS 3; pyrargyrite or dark red silver ore, Ag 3 SbS 3; stephanite, Ag 5 SbS 4; miargyrite, AgSbS2; stromeyerite, CuAgS; polybasite, 9(Cu 2 S,Ag 2 S) (Sb 2 S 3, As 2 S 3); cerargyrite or horn silver, AgCI; bromite or bromargyrite, AgBr; embolite, Ag(C1,Br); iodite or iodargyrite, AgI.
Silver bromide, AgBr, constitutes the mineral bromargyrite or bromyrite, found in Mexico and Chile.
The chloro-bromide and bromide of silver were also included under this term until they were distinguished chemically in 1841 and 1842, and described under the names embolite and bromargyrite (or bromyrite) respectively; the chloride then came to be distinguished as chlorargyrite, though the name cerargyrite is often now applied to this alone.
The colour varies somewhat with the chemical composition, being grey or colourless in chlorargyrite, greenish-grey in embolite and bromargyrite, and greenish-yellow to orange-yellow in iodembolite.