Curium hydroxide
Curium hydroxide  is a radioactive compound first discovered in measurable quantities in 1947. It is composed of a single curium atom and three hydroxy groups. It was the first curium compound ever isolated. Curium hydroxide is an anhydrous colorless or light-yellow amorphous gelatinous solid that is insoluble in water. Due to self-irradiation, the crystal structure of  decomposes within one day ( has a half-life of 18.11 years); for  the same process takes 4 to 6 months ( has a half-life of 432.2 years). See also
 Curium(III) oxide

References

Curium compounds
Hydroxides
Substances discovered in the 1940s