Californium(III) fluoride is a yellow-green solid[2] and has two crystalline structures that are temperature dependent. At low temperatures the orthorhombic structure (YF 3 type) is found with lattice constantsa = 665.3(3) pm, b = 703.9(1) pm and c = 439.3(3) pm. At higher temperatures it forms a trigonal system (LaF 3 type) with: a = 694.5(3) pm and c = 710.1(2) pm. Here, each californium atom is surrounded by nine fluorine atoms in a distorted triply-capped trigonal-prismatic structure.[3][4]