The facts
What orpiment actually is
Mineralogically, orpiment is orpiment — As₂S₃, crystallising in the monoclinic system.
The colour is caused by as–S charge transfer giving lemon to golden yellow with a pearly to resinous lustre. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 2.4–3.02, and the specific gravity sits near 3.49; cleavage is perfect {010}; flexible, sectile laminae.
Where orpiment comes from
The recognised sources are Shimen, Hunan, China, Twin Creeks Mine, Humboldt County, Nevada, USA, Quiruvilca, Peru and Lukhumi, Georgia.
Origin affects price in this material, so we name the locality on every quote rather than the country. "African" or "Asian" tells a buyer nothing.
How orpiment is treated
Untreated. Historically ground as the pigment King's yellow until its arsenic content ended the practice. Light-sensitive like realgar and equally toxic; the perfect cleavage makes it soft, flexible and unworkable as a gem.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What orpiment is confused with
The usual confusions are Realgar, Sulphur, Gold and Wulfenite.
The separation is rarely a matter of opinion: refractive index 2.4–3.02 and specific gravity 3.49 settle most of it in a minute, and magnification settles the rest.
What orpiment is used for
Orpiment is bought by mineral collecting and pigments — and each of those trades wants a different form of the same material.
We quote each application in the unit that trade actually buys in, by the specimen or by the tonne.
Durability and care
Orpiment is 1.5–2 on the Mohs scale, with perfect {010}; flexible, sectile laminae cleavage.
Below about 5.5 a stone will be scratched by ordinary household dust, which is largely quartz. That does not make it unusable — it makes it a pendant, an earring or an object rather than a ring worn every day.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What orpiment costs
Indicative pricing for orpiment is Specimens $30–$3,000.
That is a range, not a quote. Colour, size, clarity, cut and origin move the figure a long way inside it, and the only honest price is one given against a specific stone. Send us what you need and we will price it.
Questions
Is orpiment treated, and how?
Untreated. Historically ground as the pigment King's yellow until its arsenic content ended the practice. Light-sensitive like realgar and equally toxic; the perfect cleavage makes it soft, flexible and unworkable as a gem.
Where does orpiment come from?
Shimen, Hunan, China, Twin Creeks Mine, Humboldt County, Nevada, USA, Quiruvilca, Peru and Lukhumi, Georgia. Origin affects price, so we name the locality rather than the country on every quote.
Is orpiment hard enough to wear every day?
Not really. At 1.5–2 on the Mohs scale it is softer than the quartz dust in ordinary household dirt, so it scratches with wear. It suits pendants, earrings and objects better than a daily ring.
How much does orpiment cost?
Indicatively Specimens $30–$3,000. Colour, size, clarity and origin move the price a long way within that, so treat it as a range and ask for a quote against a specific stone.
What is orpiment confused with?
Most often Realgar, Sulphur, Gold and Wulfenite. A refractive index of 2.4–3.02 and a specific gravity near 3.49 separate it quickly.
Related stones
Looking for orpiment?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
Ask about orpiment