▁B - 1 2 , ▁while ▁c ob alt - 6 0 ▁is ▁a ▁component ▁of ▁nuclear ▁fall out ▁and ▁can ▁be ▁dangerous ▁in ▁large ▁enough ▁quantities ▁due ▁to ▁its ▁radio activity . ▁ ▁Nick el ▁ ▁Nick el ▁( N i ) ▁is ▁an ▁element ▁in ▁group   1 0 . ▁Nick el ▁is ▁rare ▁in ▁the ▁Earth ' s ▁cr ust , ▁mainly ▁due ▁to ▁the ▁fact ▁that ▁it ▁react s ▁with ▁o xygen ▁in ▁the ▁air , ▁with ▁most ▁of ▁the ▁nick el ▁on ▁Earth ▁coming ▁from ▁nick el ▁iron ▁meteor ites . ▁However , ▁nick el ▁is ▁very ▁abund ant ▁in ▁the ▁Earth ' s ▁core ; ▁along ▁with ▁iron ▁it ▁is ▁one ▁of ▁the ▁two ▁main ▁components . ▁Nick el ▁is ▁an ▁important ▁component ▁of ▁st ain less ▁steel , ▁and ▁in ▁many ▁super allo ys . ▁ ▁Co pper ▁ ▁Co pper ▁( C u ) ▁is ▁an ▁element ▁in ▁group   1 1 . ▁Co pper ▁is ▁one ▁of ▁the ▁few ▁met als ▁that ▁is ▁not ▁white ▁or ▁gray ▁in ▁color , ▁the ▁only ▁others ▁being ▁gold ▁and ▁ca es ium . ▁Co pper ▁has ▁been ▁used ▁by ▁humans ▁for ▁thousands ▁of ▁years ▁to ▁provide ▁a ▁re dd ish ▁t int ▁to ▁many ▁objects , ▁and ▁is ▁even ▁an ▁essential ▁nut ri ent ▁to ▁humans , ▁although ▁too ▁much ▁is ▁poison ous . ▁Co pper ▁is ▁also ▁commonly ▁used ▁as ▁a ▁wood ▁pres erv ative ▁or ▁fung ic ides . ▁ ▁Z inc ▁ ▁Z inc