auripigmentum

Latin auripigmentum is a compound of aurum ('gold') and pigmentum ('pigment, paint'). The Romans saw the brilliant yellow mineral and named it for what it resembled: the color of gold. The mineral is arsenic trisulfide (As₂S₃), and it occurs naturally as a soft, flaky stone with a golden-yellow luster. Pliny the Elder described it in his Natural History (77 CE) and noted that it came from mines in Syria and Pontus.

Orpiment was prized across the ancient world. Egyptian painters used it on tomb walls. Chinese alchemists called it cí huáng (雌黄) and valued it for both pigment and proto-chemistry. In medieval Islamic manuscripts, orpiment was the standard yellow for illumination. The pigment was brilliant, opaque, and warm—qualities that made it irresistible despite its toxicity.

The toxicity was severe. Orpiment is chemically related to realgar (arsenic disulfide) and both release arsenic when heated or dissolved. Miners suffered chronic arsenic poisoning. Artists who licked their brushes—a common practice for creating fine points—ingested the compound. Furthermore, orpiment reacted badly with copper and lead pigments, blackening any painting where it was mixed carelessly.

Orpiment faded from Western use in the 1800s as cadmium yellow and chrome yellow offered equally vivid alternatives without the arsenic. But it persists in traditional art practices in parts of South and Southeast Asia. Conservation scientists can identify orpiment in medieval manuscripts by its distinctive Raman spectroscopy signature—a golden ghost still glowing in parchment.