The facts
What flint actually is
Flint is classified as chalcedony (microcrystalline quartz), with the composition SiO₂. It crystallises in the trigonal (cryptocrystalline) system.
Colour comes from grey to black from included organic carbon and iron sulphides, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.530–1.539. Specific gravity around 2.57–2.64. Cleavage: none (conchoidal fracture). Those three numbers separate it from most of what imitates it.
Where flint comes from
Flint is produced at Grimes Graves, Norfolk, England, Rügen, Germany and Dordogne, France.
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 flint is treated
Untreated. Heat treatment was used prehistorically to improve knapping quality and is still used by modern knappers; it is not a gem treatment.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What flint is confused with
In the trade flint is most often mistaken for, or substituted by, Obsidian, Jasper, Basalt or Black chalcedony.
The separation is rarely a matter of opinion: refractive index 1.530–1.539 and specific gravity 2.57–2.64 settle most of it in a minute, and magnification settles the rest.
What flint is used for
Demand for flint comes from carving and sculpture, decorative objects, mineral collecting and heavy industry, which is why one price per carat never covers it.
We quote each application in the unit that trade actually buys in, by the block, by the piece or by the specimen.
Durability and care
Hardness 6.5–7; cleavage none (conchoidal fracture). 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 flint costs
As a guide, flint trades around Nominal; priced as rough or as worked artefact.
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 flint treated, and how?
Untreated. Heat treatment was used prehistorically to improve knapping quality and is still used by modern knappers; it is not a gem treatment.
Where does flint come from?
Grimes Graves, Norfolk, England, Rügen, Germany and Dordogne, France. Origin affects price, so we name the locality rather than the country on every quote.
Is flint hard enough to wear every day?
Yes. At 6.5–7 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 flint cost?
Indicatively Nominal; priced as rough or as worked artefact. 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 flint confused with?
Most often Obsidian, Jasper, Basalt and Black chalcedony. A refractive index of 1.530–1.539 and a specific gravity near 2.57–2.64 separate it quickly.
What is flint used for besides jewellery?
carving and sculpture, decorative objects, mineral collecting and heavy industry. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for flint?
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 flint