The facts
What brochantite actually is
Brochantite is classified as brochantite, with the composition Cu₄(SO₄)(OH)₆. It crystallises in the monoclinic system.
Colour comes from cu²⁺ in a basic sulphate; emerald to blackish-green acicular crystals, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.728–1.800. Specific gravity around 3.97. Cleavage: perfect {100}. Those three numbers separate it from most of what imitates it.
Where brochantite comes from
Brochantite is produced at Milpillas Mine, Sonora, Mexico, Bisbee, Arizona, USA, Tsumeb, Namibia and Chuquicamata, Chile.
The locality is part of the description, not a footnote — two stones of the same weight from two of these places are not the same stone.
How brochantite is treated
Untreated. It is also the green patina component that forms on copper roofs and bronze statues in polluted, sulphate-rich air — the same species, just anthropogenic.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What brochantite is confused with
In the trade brochantite is most often mistaken for, or substituted by, Malachite, Antlerite, Atacamite or Olivenite.
The separation is rarely a matter of opinion: refractive index 1.728–1.800 and specific gravity 3.97 settle most of it in a minute, and magnification settles the rest.
What brochantite is used for
Demand for brochantite comes from mineral collecting, which is why one price per carat never covers it.
We quote each application in the unit that trade actually buys in, by the specimen.
Durability and care
Hardness 3.5–4; cleavage perfect {100}. That combination decides what it can safely be set into.
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 brochantite costs
As a guide, brochantite trades around Specimens $30–$1,200.
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 brochantite treated, and how?
Untreated. It is also the green patina component that forms on copper roofs and bronze statues in polluted, sulphate-rich air — the same species, just anthropogenic.
Where does brochantite come from?
Milpillas Mine, Sonora, Mexico, Bisbee, Arizona, USA, Tsumeb, Namibia and Chuquicamata, Chile. Origin affects price, so we name the locality rather than the country on every quote.
Is brochantite hard enough to wear every day?
Not really. At 3.5–4 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 brochantite cost?
Indicatively Specimens $30–$1,200. 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 brochantite confused with?
Most often Malachite, Antlerite, Atacamite and Olivenite. A refractive index of 1.728–1.800 and a specific gravity near 3.97 separate it quickly.
Related stones
Looking for brochantite?
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 brochantite