Schmitterite, UTeO
5, was found in a sample of the mineralogical collection of the Natural History Museum of the University of Florence. The sample
is from the Bambolla mine, Moctezuma, Sonora, Mexico and the mineral occurs as very rare crystals associated with emmonsite.
Schmitterite is orthorhombic, space group Pca21, with the following unit-cell parameters: a = 10.163(1), b = 5.361(1), c = 7.865(1) Å, V = 428.5(1) Å3, and Z = 4. EDS chemical analyses showed only uranium and tellurium to be present. The crystal structure has been solved and refined
to R = 2.28%. It consists of edge-sharing chains of UO7 pentagonal bipyramids parallel to [001] linked into a framework by TeO4 polyhedra. The crystal-chemical reasons for the choice of the non-centrosymmetric arrangement and the structural relationships
with other natural tellurites are outlined.