The facts
What andalusite actually is
The species behind andalusite is andalusite, Al₂SiO₅; it forms in the orthorhombic system.
Fe³⁺ and Mn; the strong green/red/brown pleochroism is the defining visual feature, not a colour change 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 1.629–1.650 and a specific gravity of about 3.13–3.21, with distinct {110}, indistinct {100} cleavage.
Where andalusite comes from
Commercial material comes from Santa Maria de Itabira, Minas Gerais, Brazil, Ratnapura, Sri Lanka, El Cardoso de la Sierra, Guadalajara, Spain (type locality — not in Andalusia, despite the name) and Antsirabe, Madagascar.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How andalusite is treated
Untreated. Cutters deliberately orient stones to show two pleochroic colours at once, which is what buyers are paying for; it is genuinely trichroic and not a colour-change gem, and it should not be sold as alexandrite-like. Refractory-grade andalusite is a major industrial commodity, unrelated to the gem trade.
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 andalusite is confused with
Watch for Alexandrite, Chrysoberyl, Sphene, Tourmaline and Smoky quartz — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.629–1.650 and specific gravity 3.13–3.21 settle most of it in a minute, and magnification settles the rest.
What andalusite is used for
The trades that buy andalusite are jewellery, mineral collecting, refractories and heavy industry. 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 carat, by the specimen or by the tonne.
Durability and care
Andalusite is 7–7.5 on the Mohs scale, with distinct {110}, indistinct {100} 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 andalusite costs
Expect roughly $30–250/ct, 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 andalusite treated, and how?
Untreated. Cutters deliberately orient stones to show two pleochroic colours at once, which is what buyers are paying for; it is genuinely trichroic and not a colour-change gem, and it should not be sold as alexandrite-like. Refractory-grade andalusite is a major industrial commodity, unrelated to the gem trade.
Where does andalusite come from?
Santa Maria de Itabira, Minas Gerais, Brazil, Ratnapura, Sri Lanka, El Cardoso de la Sierra, Guadalajara, Spain (type locality — not in Andalusia, despite the name) and Antsirabe, Madagascar. Origin affects price, so we name the locality rather than the country on every quote.
Is andalusite hard enough to wear every day?
Yes. At 7–7.5 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 andalusite cost?
Indicatively $30–250/ct. 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 andalusite confused with?
Most often Alexandrite, Chrysoberyl, Sphene, Tourmaline and Smoky quartz. A refractive index of 1.629–1.650 and a specific gravity near 3.13–3.21 separate it quickly.
What is andalusite used for besides jewellery?
mineral collecting, refractories and heavy industry. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for andalusite?
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 andalusite