The facts
What chalcanthite actually is
The species behind chalcanthite is chalcanthite, CuSO₄·5H₂O; it forms in the triclinic system.
Cu²⁺ hydrated sulphate giving a strong sky to sapphire blue 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 1.514–1.543 and a specific gravity of about 2.28, with imperfect {110} cleavage.
Where chalcanthite comes from
Commercial material comes from Chuquicamata, Chile, Planet Mine, La Paz County, Arizona, USA, Rio Tinto, Huelva, Spain and Cyprus (ancient workings).
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How chalcanthite is treated
The great majority of large blue 'chalcanthite' crystal clusters for sale are laboratory-grown on a matrix, sometimes on a real rock or even on a sponge, and honest dealers label them as such. Chalcanthite is water-soluble and deliquescent: natural specimens dissolve in humid air and must be kept sealed. Toxic if ingested.
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 chalcanthite is confused with
Watch for Laboratory-grown chalcanthite, Azurite, Linarite and Copper sulphate crystals — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.514–1.543 and specific gravity 2.28 settle most of it in a minute, and magnification settles the rest.
What chalcanthite is used for
The trades that buy chalcanthite 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
Chalcanthite is 2.5 on the Mohs scale, with imperfect {110} 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 chalcanthite costs
Expect roughly Lab-grown clusters $10–$60; genuine natural specimens $100–$2,000, 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 chalcanthite treated, and how?
The great majority of large blue 'chalcanthite' crystal clusters for sale are laboratory-grown on a matrix, sometimes on a real rock or even on a sponge, and honest dealers label them as such. Chalcanthite is water-soluble and deliquescent: natural specimens dissolve in humid air and must be kept sealed. Toxic if ingested.
Where does chalcanthite come from?
Chuquicamata, Chile, Planet Mine, La Paz County, Arizona, USA, Rio Tinto, Huelva, Spain and Cyprus (ancient workings). Origin affects price, so we name the locality rather than the country on every quote.
Is chalcanthite hard enough to wear every day?
Not really. At 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 chalcanthite cost?
Indicatively Lab-grown clusters $10–$60; genuine natural specimens $100–$2,000. 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 chalcanthite confused with?
Most often Laboratory-grown chalcanthite, Azurite, Linarite and Copper sulphate crystals. A refractive index of 1.514–1.543 and a specific gravity near 2.28 separate it quickly.
Related stones
Looking for chalcanthite?
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 chalcanthite