雄黃
Realgar \Re*al"gar\, n. [F. r['e]algar, Sp. rejalgar, Ar. rahj al gh[=a]r powder of the mine.] (Min.) Arsenic sulphide, a mineral of a brilliant red color; red orpiment. It is also an artificial product.
realgar n : a rare soft orange mineral consisting of arsenic sulphide; an important ore of arsenic