cerargyrite

cerargyrite, gray, very heavy halide mineral composed of silver chloride (AgCl); it is an ore of silver. It forms a complete solid-solution series with bromyrite, silver bromide (AgBr), in which bromine completely replaces chlorine in the crystal structure. These are secondary minerals that commonly occur as alteration products of native silver, silver sulfides, and sulfosalts in silver deposits that have been oxidized by weathering. They are often found as crusts, coatings, or hornlike masses with native silver, wad, and limonite and are common in Germany, Chile, and the western United States. For detailed physical properties, see halide mineral (table).