Silvery-grey as a metal; brown as terbium oxide
Terbium is ductile and easily malleable. In air it is relatively stable as a metal and it forms a passivating protective layer. Due to its high chemical activity, it should be packaged under protective gas or paraffin oil.
It is applied in neodymium-iron-boron-magnets to increase the coercivity. Moreover, it is used in luminescent material to create green color effects. In dental medicine, terbium is used in the manufacture of all-ceramic systems.