Arsenopyrite is the most abundant arsenic mineral and the primary ore of arsenic metal. It has the formula FeAsS and typically occurs in hydrothermal veins, metamorphic rocks, and magmatic deposits.
Realgar is a sulfide mineral of arsenic and sulfur, with the formula As4S4. It has a bright red-orange color and a resinous luster. It is often associated with other arsenic minerals, such as orpiment, and is found in volcanic, sedimentary, and hydrothermal environments.
Orpiment is another sulfide mineral of arsenic and sulfur, with the formula As2S3. It has a vivid yellow color and a pearly luster. It often occurs together with realgar, and is also found in volcanic, sedimentary, and hydrothermal settings. It was historically used as a pigment and a poison.
Enargite is a copper-arsenic sulfide mineral, with the formula Cu3AsS4. It has a gray-black color and a metallic luster. It is a major ore of copper in some deposits, and also contains trace amounts of gold and silver. It forms in high-temperature hydrothermal veins and breccias.
Tennantite is a copper-iron-arsenic sulfide mineral, with the formula (Cu,Fe)12As4S13. It has a dark gray color and a metallic luster. It is a member of the tetrahedrite group, and often occurs with other sulfide minerals, such as chalcopyrite, galena, and sphalerite. It is an important ore of copper and silver in some regions, and also contains traces of gold, zinc, and mercury. It forms in hydrothermal and metamorphic environments.