Radioactivity: slightly radioactive

Radioactive elements: The most stable isotope is very long-lived, with a half-life of over four million years.

43Tc
Technetiumshiny gray metal
83Bi
Bismuthlustrous brownish silver
92U
Uraniumsilvery gray metallic; corrodes to a spalling black oxide coat in air
93Np
Neptuniumsilvery metallic
94Pu
Plutoniumsilvery white, tarnishing to dark gray in air
96Cm
Curiumsilvery metallic, glows purple in the dark