Gummite is not a definitive mineral species, but rather an unspecific mixture of secondary uranium minerals, especially Becquerelite, Boltwoodite, Clarkeite, Curite, Fourmarierite, Kasolite, Soddyite, and Uranophane. It lacks a definitive chemical formula and crystal structure, though it is still listed as a mineral in many mineral guides.

Gummite forms from the oxidation of Uraninite and is present in most uranium deposits. It often forms as a partial alteration of Uraninite, where the inner core remains dull-colored Uraninite, and the outer layers as brightly colored Gummite. The origination of the name Gummite is unknown, but it is presumably named for its rubber or gum-like consistency. Gummite is a radioactive mineral, and should be stored with all the precautions exercised with radioactive minerals.