Chrisstanleyite, Ag₂Pd₃Se₄, is a selenide mineral that crystallizes in high saline, acidic hydrothermal solution at low temperatures as part of selenide vein inclusions in and alongside calcite veins. It tends be found in assemblages of other selenides: jagueite, naumannite, fischesserite, oosterboschite, and tiemannite, and it is a solid solution mineral with jagueite Cu₂Pd₃Se₄ in which it shares a unique crystal structure that has not been identified elsewhere (Paar et al. 1998; Nickel 2002; Paar et al. 2004). Chrisstanleyite and jagueite are unlike the other minerals of the selenide family as they do not have a sulfide analogue (Topa et al. 2006). First discovered by Dr. Werner Paar from a sample received from Hope's Nose, Torquay, Devon, England, chrisstanleyite has since been discovered in the Pilbara region of Western Australia and in El Chire, La Rioja, Argentina. Chrisstanleyite was named after the Deputy Head and Associate Keeper at the Department of Mineralogy at The Natural History Museum in London, Dr. Chris Stanley (born 1954), for his work and contributions in ore mineralogy (Paar et al. 1998), which include identifying over 40 minerals and writing over 100 peer reviewed articles.