The facts
What simpsonite actually is
The species behind simpsonite is aluminium tantalate, Al₄(Ta,Nb)₃(O,OH,F)₁₄; it forms in the trigonal system.
Ta and Nb with trace Fe give pale orange to brownish yellow 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 1.994–2.040 and a specific gravity of about 5.90–7.30, with poor cleavage.
Where simpsonite comes from
Commercial material comes from Tabba Tabba pegmatite, Pilbara, Western Australia, Alto do Giz, Rio Grande do Norte, Brazil and Onça, Paraíba, Brazil.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How simpsonite is treated
Untreated. One of the hardest tantalates and among the rarer faceted gems; almost all known cut stones are under two carats.
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 simpsonite is confused with
Watch for Microlite, Cassiterite and Zircon — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.994–2.040 and specific gravity 5.90–7.30 settle most of it in a minute, and magnification settles the rest.
What simpsonite is used for
The trades that buy simpsonite 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
Hardness 7–7.5; cleavage poor. That combination decides what it can safely be set into.
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 simpsonite costs
Expect roughly Faceted stones 300–1,200 USD/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 simpsonite treated, and how?
Untreated. One of the hardest tantalates and among the rarer faceted gems; almost all known cut stones are under two carats.
Where does simpsonite come from?
Tabba Tabba pegmatite, Pilbara, Western Australia, Alto do Giz, Rio Grande do Norte, Brazil and Onça, Paraíba, Brazil. Origin affects price, so we name the locality rather than the country on every quote.
Is simpsonite 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 simpsonite cost?
Indicatively Faceted stones 300–1,200 USD/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 simpsonite confused with?
Most often Microlite, Cassiterite and Zircon. A refractive index of 1.994–2.040 and a specific gravity near 5.90–7.30 separate it quickly.
Related stones
Looking for simpsonite?
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 simpsonite