The facts
What foitite actually is
Foitite is classified as tourmaline supergroup, with the composition ☐(Fe²⁺₂Al)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃(OH). It crystallises in the trigonal system.
Colour comes from fe²⁺–Fe³⁺ intervalence charge transfer gives the blue-black to violet-blue, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.630–1.655. Specific gravity around 3.17. Cleavage: none. Those three numbers separate it from most of what imitates it.
Where foitite comes from
Foitite is produced at San Diego County, California, USA, Mount Mica, Oxford County, Maine, USA and Elba Island, Tuscany, Italy.
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 foitite is treated
Untreated. Usually occurs as thin dark overgrowths on elbaite rather than as separate gem crystals; almost never faceted.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What foitite is confused with
In the trade foitite is most often mistaken for, or substituted by, Schorl, Indicolite or Dravite.
The separation is rarely a matter of opinion: refractive index 1.630–1.655 and specific gravity 3.17 settle most of it in a minute, and magnification settles the rest.
What foitite is used for
Demand for foitite 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
Foitite is 7 on the Mohs scale, with none cleavage.
With no cleavage plane to worry about, the practical limit is abrasion rather than breakage, and it takes daily wear well.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What foitite costs
As a guide, foitite trades around Specimens 30–300 USD.
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 foitite treated, and how?
Untreated. Usually occurs as thin dark overgrowths on elbaite rather than as separate gem crystals; almost never faceted.
Where does foitite come from?
San Diego County, California, USA, Mount Mica, Oxford County, Maine, USA and Elba Island, Tuscany, Italy. Origin affects price, so we name the locality rather than the country on every quote.
Is foitite hard enough to wear every day?
Yes. At 7 on the Mohs scale with no cleavage plane, it handles daily wear well. The practical limit is gradual abrasion rather than chipping.
How much does foitite cost?
Indicatively Specimens 30–300 USD. 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 foitite confused with?
Most often Schorl, Indicolite and Dravite. A refractive index of 1.630–1.655 and a specific gravity near 3.17 separate it quickly.
Related stones
Looking for foitite?
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 foitite