Autunite is a mineral that contains uranium, it is radioactive when found in large reservoir. In it, it is possible to note amazing greenish yellow crystals that lose color and decompose in dry environments.
São Geraldo de Baixio, Minas Gerais.
It is very common and fluorescent under ultraviolet light.
The mineral is extracted and marketed to achieve uranium. Photo credit: Leonardo Miranda
Source: MM Gerdau - Museu das Minas e do Metal -