Emily Dickinson Lexicon

OR'PI-MENT, n. [L. auripigmentum; aurum, gold, and pigmentum.]

Sesqui-sulphuret of arsenic, found native and then an ore of arsenic, or artificially composed. The native orpiment appears in yellow, brilliant and seemingly talcky masses of various sizes. The red orpiment is called realgar, and is a protosulphuret of arsenic. It is more or less lively and transparent, and often crystalized in bright needles. In this form it is called ruby of arsenic. Fourcroy. Nicholson. Encyc. Ure.