Californium a nuclear explosion. Californium is not a major radionuclide at United States Department of Energy legacy sites since it was not produced in large quantities. Californium was once believed to be produced in supernovas, as their decay matches the 60-day half-life of Cf. However, subsequent studies failed to demonstrate any californium spectra, and supernova light curves are now thought to follow the decay of nickel-56. The transuranic elements from americium to fermium, including californium, occurred naturally in the natural nuclear fission reactor at Oklo, but no longer do so. Californium is produced in nuclear reactors and particle accelerators. Californium-250 is
Californium compounds emerald green compound with a hexagonal structure that can be prepared by reacting CfO with hydrochloric acid at 500 °C. CfCl is then used as a feeder stock to form the yellow-orange triiodide CfI, which in turn can be reduced to the lavender-violet diiodide CfI. Californium(III) fluoride (CfF) is a yellow-green solid with a crystal symmetry that gradually changes from orthorhombic to trigonal when heated above room temperature. Californium(IV) fluoride (CfF) is a bright green solid with a monoclinic crystal structure. Californium(II) iodide (CfI) is a deep purple solid with a stable rhombohedral structure at room temperature and an unstable