# Orpiment and realgar

**Auripigmentum*, *sandaraca**

**Known today as.** Yellow and red arsenic sulfides.

Kind: Mineral  
Poisoning: Mercury, arsenic, lead, and antimony (https://thethinkingpress.org/materia-medica/poisons/heavy-metal)  
Deadly: yes

> **Deadly.** 

## What was it used for?

Caustics for ulcers and depilatories; the yellow and red pigments of painters.

## What does modern science say?

Arsenic compounds, poisonous by mouth and in the dust.

## Pharmacognosy and toxicology

- **arsenic trisulfide**: orpiment
- **arsenic sulfide**: realgar

**Mechanism.** The sulfides are poorly soluble, so less poisonous than white arsenic by mouth; roasting gives the oxide.

**Dose.** Grams, by mouth; the fumes are the greater hazard.

**Standing.** Realgar remains in some Chinese preparations, against advice.

## What did the older authorities say?

**Pliny.** Tells that Caligula, greedy for gold, had orpiment smelted to extract it, and got almost none.

## Sources

- Pliny, *Natural History* XXXIII.
- Liu, J., et al. (2008). *Experimental Biology and Medicine* 233.

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*Orpiment and realgar.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-09-25. The Thinking Press. https://thethinkingpress.org/materia-medica/orpiment-and-realgar

Historical description, not medical advice.