The facts
What erythrite actually is
The species behind erythrite is vivianite group, Co₃(AsO₄)₂·8H₂O; it forms in the monoclinic system.
Co²⁺ giving the crimson to magenta colour that prospectors used as an indicator for cobalt and silver ore is responsible for the colour — and the chromophore, not the name, is what decides whether a colour is stable.
On the instruments it reads a refractive index of 1.626–1.701 and a specific gravity of about 3.06, with perfect {010}; flexible, sectile laminae cleavage.
Where erythrite comes from
Commercial material comes from Bou Azzer, Morocco, Schneeberg, Saxony, Germany, Cobalt, Ontario, Canada and Mount Cobalt, Queensland, Australia.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How erythrite is treated
Untreated. Bladed Bou Azzer crystals are the benchmark. Extremely soft and fragile, contains arsenic and cobalt, and is never cut for wear; specimens should not be handled directly or washed.
We state the treatment on every stone, including when the honest answer is that it cannot be determined. A treatment disclosed is a fact; a treatment discovered later is a refund.
What erythrite is confused with
Watch for Roselite, Cobaltoan calcite, Rhodochrosite and Realgar — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.626–1.701 and specific gravity 3.06 settle most of it in a minute, and magnification settles the rest.
What erythrite is used for
The trades that buy erythrite are mineral collecting. They do not want the same thing, and they do not pay in the same unit.
We quote each application in the unit that trade actually buys in, by the specimen.
Durability and care
Erythrite is 1.5–2.5 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 erythrite costs
Expect roughly Specimens $40–$4,000, depending on quality.
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 erythrite treated, and how?
Untreated. Bladed Bou Azzer crystals are the benchmark. Extremely soft and fragile, contains arsenic and cobalt, and is never cut for wear; specimens should not be handled directly or washed.
Where does erythrite come from?
Bou Azzer, Morocco, Schneeberg, Saxony, Germany, Cobalt, Ontario, Canada and Mount Cobalt, Queensland, Australia. Origin affects price, so we name the locality rather than the country on every quote.
Is erythrite hard enough to wear every day?
Not really. At 1.5–2.5 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 erythrite cost?
Indicatively Specimens $40–$4,000. 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 erythrite confused with?
Most often Roselite, Cobaltoan calcite, Rhodochrosite and Realgar. A refractive index of 1.626–1.701 and a specific gravity near 3.06 separate it quickly.
Related stones
Looking for erythrite?
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 erythrite