orpiment
Arsenic trisulphide, occurring naturally in crystals or massive deposits, formerly used as a dye or pigment.
countable, uncountable
Jeremiah found himself indoors, perfecting his Draftsmanship, bending all day over the work-table, grinding and mixing his own Inks,— siftings and splashes ev'rywhere of King's Yellow, Azure, red Orpiment, Indian lake, Verdigris, Indigo, and Umber.
Where it comes from
From Middle English orpyment, from Old French orpiment, from Latin auripigmentum (“orpiment”), from aurum (“gold”) + pigmentum (“pigment”).
Adapted from the Wiktionary entry orpiment (CC BY-SA 4.0).