Structure of a new natural tungstate arsenate, [Ca2Y(AsO4)(WO4)2], structurally related to scheelite

The structure of the new natural tungstate arsenate [Ca2Y(AsOa)(WO4)2] found in the Alpine fissures of the Pizzo Cervandone Area (Ossola Valley, Italy) is reported. It conforms to the scheelite-type structure and consists of layers with composi t ion YAsO4 and CaWO4 stacked in an orderly manner along [001] in the molar ratio 1:2.