[7] Hagendorfite is in the monoclinic crystal class; the mineral's internal symmetry consists of three axes with unequal length.

A single refractive index is given when two rays of light vibrate in the mineral's circular section and move along the optic axes.

Hagendorfite occurs in complex granite course-grained rocks called pegmatites or in the phosphate nodules in shale.

Although hagendorfite was first discovered in Bavaria, Germany, it has since been found in the Southern Province in Rwanda,[9] the Sowie Mountains in Poland,[10] and New Hampshire in the US.

Hagendorfite is associated with the dickinsonite series and with other mineral members including varulite, alluarrdite, and manganalluaudite.