Zircon is quite often weakly radioactive, with up to 4% of the zirconium being substituted by thorium or uranium, which destroys its crystalline form (metamict). Some varieties of zircon (those with radioactive elements) are thermoluminescent and will glow intensely for a moment (once only) when heated. Cyrtolite is a radioactive zircon containing yttrium and uranium. Heating may also restore the crystal structure of the metamict (radiation-damaged) varieties, and can also change the colour of zircons.

Ores and Minerals of Uranium
Pitchblend, Uraninite, Thorianite, Samarskite, Autunite, Copper Uranite, Torbernite, Uranophane, Zippeite.
The main ores are highly radioactive and very heavy: Uraninite, UO2 and pitchblende, U3O8, are hard and black; carnotite, K2(UO2)(VO4)2·2H2O, soft, yellow and powdery; thorianite, (Th,U)O2, black and cubic; and samarskite, (Y,Ce,U,Ca,Pb)(Nb,Ta,Ti,Sn)2O6 which contains many valuable elements.

Phosphates contain great reserves of uranium: the lime yellow autunite, Ca(UO2)2(PO4)2·10-12H2O fluoresces yellow green in ultraviolet light and has a mica-like cleavage, as does the related grass green torbernite, copper uranite, Cu[UO2PO4]2·8-12H2O and yellow uranophane, CaH2[UO2SiO4]·5H2O which are rarer.

Zippeite, U2SO10·3-6H2O, a complex hydrated uranium sulphate which results from the decomposition of pitchblende and occurs as a powdery bright yellow coating was once used as a yellow pigment in paints until it's radioactivity was discovered.

Niobium can also occur in Euxenite, (Y,Er,Ce,La,U)(Nb,Ti,Ta)2(O,OH)6, and polycrase, (Y,Er,Ce,La,U)(Ti,Nb,Ta)(O,OH)6, which are commonly metamict (altered by radiation).

Ores of Radium
Ores include uraninite, UO2; pitchblende (UO2,U3O8) at a concentration of 1 part in 7 million, and some carnotite sands, K2(UO2)2(VO4)2·H2O, and is also present in all uranium minerals from the radioactive decay chain of uranium-238 which produces radium-226, amongst other elements. It also occurs in broggerite, and cleveite. It is present in sea water at the insignificant dilution of 1 part in 1017, and concentrates in the bones of the human body where it is found at a level of a few parts in 1015.

Ores & Minerals of Praeseodymium
The element occurs along with other rare earth elements in a variety of minerals, of which monazite, (Ce,La,Nd,Th)PO4 and bastanite are two principal commercial sources.