Nep*tu"ni*um (?), n. [NL.]
A new metallic element, of doubtful genuineness and uncertain indentification, said to exist in certain minerals, as columbite.
<-- a radioactive element, produced in reactors from Pt or U; At. num. = 93, Sym. Np, At. Wt. 237.0482 [MW10] -->
© Webster 1913.