Emily Dickinson Lexicon

U-RA'NI-UM, n. [Gr. ουρανος, heaven, or a planet so called.]

A metal discovered in 1789 by Klaproth, in the mineral called pechblend. It is occasaonally found native in uran-ocher and uran-mica; but more generally it is obtained from pechblend, in which it exists with iron, copper, lead, and sometimes with arsenic, cobalt and zink. Uranium is of a reddish-brown color, has a metallic luster, and is commonly obtained in a crystalline form. It suffers no change from exposure to the air at common temperatures, but when heated in open vessels it absorbs, oxygen and is converted into a protoxyd. Henry.