Paradamite

Paradamite is a very rare zinc arsenate mineral with the chemical formula Zn2(AsO4)(OH). It is closely related to the better-known mineral adamite: both have the same chemical composition, but the atoms are arranged differently in the crystals. Because of this different structure, paradamite and adamite belong to different crystal systems (triclinic for paradamite, orthorhombic for adamite) and are considered polymorphs of each other. In the mineral list of the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA–CNMNC), paradamite has the approved symbol Prd. Paradamite was first described in 1956 by American mineralogist George Switzer from specimens collected at the Ojuela Mine, Mapimí, Durango, Mexico, which remains the type and best-known locality for Palenzonaite. It forms as a secondary mineral in the oxidised parts of polymetallic ore deposits and is typically associated with other zinc arsenates such as adamite and legrandite.