It occurs as an oxidation product of uranium minerals in granite pegmatites and hydrothermal deposits.

Associate minerals include metaautunite, torbernite, phosphuranylite, saleeite, uranophane and sabugalite.

[8] One of the other locations of autunite includes Autun, France, the type locality and namesake of the mineral.

[10][6] If the mineral dries out, it can lose its water content and convert to meta-autunite-I, which can turn into meta-autunite-II after heating.

For scientific studies it is recommended to store the mineral in a sealed container to minimize the water loss.