The facts
What cassiterite actually is
Cassiterite is classified as cassiterite, with the composition SnO₂. It crystallises in the tetragonal system.
Colour comes from fe and Ta/Nb substitution; near-colourless when pure, usually brown to black, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.997–2.093. Specific gravity around 6.8–7.1. Cleavage: imperfect {100}, indistinct {110}. Those three numbers separate it from most of what imitates it.
Where cassiterite comes from
Cassiterite is produced at Viloco and Huanuni, Bolivia, Cornwall (St Agnes, Wheal Rock), England, Yaogangxian, Hunan, China and Erongo, Namibia.
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 cassiterite is treated
Untreated. Faceted cassiterite is a connoisseur stone with brilliance close to diamond thanks to the high RI, but its very high density makes it feel wrong in a mounting and it is rarely worn.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What cassiterite is confused with
In the trade cassiterite is most often mistaken for, or substituted by, Sphalerite, Zircon, Rutile or Black tourmaline.
The separation is rarely a matter of opinion: refractive index 1.997–2.093 and specific gravity 6.8–7.1 settle most of it in a minute, and magnification settles the rest.
What cassiterite is used for
Demand for cassiterite comes from mineral collecting, jewellery, heavy industry and metallurgy, 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, by the carat or by the tonne.
Durability and care
Cassiterite is 6–7 on the Mohs scale, with imperfect {100}, indistinct {110} cleavage.
Hardness is not the whole story. Perfect cleavage means the stone can split cleanly if struck along the wrong plane, whatever its Mohs number, so a protective setting matters more here than the hardness suggests.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What cassiterite costs
As a guide, cassiterite trades around Crystal specimens $50–$5,000; faceted stones $50–$300/ct.
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 cassiterite treated, and how?
Untreated. Faceted cassiterite is a connoisseur stone with brilliance close to diamond thanks to the high RI, but its very high density makes it feel wrong in a mounting and it is rarely worn.
Where does cassiterite come from?
Viloco and Huanuni, Bolivia, Cornwall (St Agnes, Wheal Rock), England, Yaogangxian, Hunan, China and Erongo, Namibia. Origin affects price, so we name the locality rather than the country on every quote.
Is cassiterite hard enough to wear every day?
With care. It is 6–7 on the Mohs scale, which is hard enough, but imperfect {100}, indistinct {110} cleavage means it can split if struck at the wrong angle. Use a protective setting and avoid ultrasonic cleaning.
How much does cassiterite cost?
Indicatively Crystal specimens $50–$5,000; faceted stones $50–$300/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 cassiterite confused with?
Most often Sphalerite, Zircon, Rutile and Black tourmaline. A refractive index of 1.997–2.093 and a specific gravity near 6.8–7.1 separate it quickly.
What is cassiterite used for besides jewellery?
mineral collecting, heavy industry and metallurgy. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for cassiterite?
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 cassiterite