The facts
What datolite actually is
Datolite is classified as datolite, with the composition CaBSiO₄(OH). It crystallises in the monoclinic system.
Colour comes from in the Michigan nodules the colour is inclusion-driven rather than ionic — copper, hematite and manganese inclusions, with micro-copper giving the reds and pinks; the chromophore in transparent facetable material is unverified, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.621–1.675. Specific gravity around 2.90–3.00. Cleavage: none — the name refers to granular varieties crumbling, not to cleavage. Those three numbers separate it from most of what imitates it.
Where datolite comes from
Datolite is produced at Keweenaw Peninsula (Centennial, Quincy, Caledonia and Delaware mines), Michigan, USA, Dal'negorsk, Primorsky Krai, Russia, Charcas, Mexico and Arendal, Norway.
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 datolite is treated
No known gem treatments; synthetic datolite is research-only. One uncorroborated trade claim holds that porous Michigan nodules are sometimes resin-stabilised. Facet rough is usually under 2 g and the largest documented cut stone is 7.85 ct, so size alone should raise questions. Separates from danburite instantly on birefringence — 0.044 gives visible doubling where danburite's 0.006 does not.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What datolite is confused with
In the trade datolite is most often mistaken for, or substituted by, Danburite, Prehnite, Colourless quartz or Apophyllite.
The separation is rarely a matter of opinion: refractive index 1.621–1.675 and specific gravity 2.90–3.00 settle most of it in a minute, and magnification settles the rest.
What datolite is used for
Demand for datolite comes from mineral collecting, carving and sculpture, decorative objects and jewellery, 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 block or by the piece.
Durability and care
Datolite is 5–5.5 on the Mohs scale, with none — the name refers to granular varieties crumbling, not to cleavage cleavage.
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 datolite costs
As a guide, datolite trades around $20–200/ct faceted; Michigan nodule cabochons priced by pattern.
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 datolite treated, and how?
No known gem treatments; synthetic datolite is research-only. One uncorroborated trade claim holds that porous Michigan nodules are sometimes resin-stabilised. Facet rough is usually under 2 g and the largest documented cut stone is 7.85 ct, so size alone should raise questions. Separates from danburite instantly on birefringence — 0.044 gives visible doubling where danburite's 0.006 does not.
Where does datolite come from?
Keweenaw Peninsula (Centennial, Quincy, Caledonia and Delaware mines), Michigan, USA, Dal'negorsk, Primorsky Krai, Russia, Charcas, Mexico and Arendal, Norway. Origin affects price, so we name the locality rather than the country on every quote.
Is datolite hard enough to wear every day?
Not really. At 5–5.5 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 datolite cost?
Indicatively $20–200/ct faceted; Michigan nodule cabochons priced by pattern. 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 datolite confused with?
Most often Danburite, Prehnite, Colourless quartz and Apophyllite. A refractive index of 1.621–1.675 and a specific gravity near 2.90–3.00 separate it quickly.
What is datolite used for besides jewellery?
mineral collecting, carving and sculpture and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for datolite?
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 datolite