pharmacosiderite
/ˌfɑːməkəˈsʌɪdərʌɪt/Mineralogy
noun
A mineral of the cubic crystal system consisting of a hydrated arsenate of iron and potassium (often also containing other elements, especially barium or sodium), and usually occurring as minute greenish or brownish crystals of cubic or tetrahedral form.
Origin
Mid 19th century; earliest use found in Charles Shepard (1804–1886). From pharmaco- + siderite, after German Pharmakosiderit.