The crystal structure of the low-temperature 2O polytype of Cu^II₃Te^VIO₆ (the mineral mcalpineite) has been determined by 3D electron diffraction (3D ED) and Rietveld refinement following X-ray powder diffraction (PXRD).

The twinned structure of the new uranium oxide mineral was refined from X-ray diffraction data and was found to contain fluorine and pentavalent uranium. The presence of pentavalent uranium is indicative of the reducing conditions under which the mineral formed. Nollmotzite is the first naturally occurring uranium oxide mineral that contains fluorine.