ABSTRACT: Lotharmeyerite, calcium bis-(zinc/manganese) bis-(arsenate) bis-(hydroxide/hydrate), Ca(Zn,Mn(3+))(2)(AsO(4))(2)(H(2)O,OH)(2), is a member of the natrochalcite group of minerals, which are characterized by the general formula AM(2)(XO(4))(2)(H(2)O,OH)(2), where A may be occupied by Pb(2+), Ca(2+), Na(+), and Bi(3+), M by Fe(3+), Mn(3+), Cu(2+), Zn(2+), Co(2+), Ni(2+), Al(3+), and Mg(2+), and X by P(V), As(V), V(V), and S(VI). The minerals in the group display either monoclinic or triclinic symmetry, depending on the ordering of chemical components in the M site. Based on single-crystal X-ray diffraction data of a sample from the type locality, Mapimi, Durango, Mexico, this study presents the first structure determination of lotharmeyerite. Lotharmeyerite is isostructural with natrochalcite
