The facts
What fossil Ammonite actually is
Fossil Ammonite is classified as fossil shell of Mesozoic cephalopods, preserved as calcite, aragonite, pyrite or as an internal mould, with the composition Calcite or aragonite CaCO3; pyritised and silicified examples occur. It crystallises in the aggregate system.
Colour comes from host sediment minerals; iridescent examples show nacre interference (see ammolite), which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.486-1.658. Specific gravity around 2.6-2.9. Cleavage: none. Those three numbers separate it from most of what imitates it.
Where fossil Ammonite comes from
Fossil Ammonite is produced at Mahajanga Basin, Madagascar (Cleoniceras, Douvilleiceras), Erfoud and Rissani, Morocco, Lyme Regis and Whitby, England (protected coastline, collection codes apply) and Bearpaw Formation, Alberta, Canada (the ammolite source).
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 fossil Ammonite is treated
Commonly acid-etched, air-abraded, polished and resin-repaired; composites assembled from several specimens are routine in the Moroccan trade. LEGAL: fossil export from Morocco technically requires permits under Article 116 of the 2015 Mining Code and is widely unpermitted in practice; Madagascar has periodically suspended fossil export; the UK has voluntary collecting codes at Lyme Regis rather than a ban. Not CITES.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What fossil Ammonite is confused with
In the trade fossil Ammonite is most often mistaken for, or substituted by, Cast resin replicas (extremely common from Morocco), Composite specimens assembled from parts or Carved and 'improved' sutures.
The separation is rarely a matter of opinion: refractive index 1.486-1.658 and specific gravity 2.6-2.9 settle most of it in a minute, and magnification settles the rest.
What fossil Ammonite is used for
Demand for fossil Ammonite comes from mineral collecting, architecture and interiors, 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 square metre or by the piece.
Durability and care
Hardness 3-4 (calcite), higher if silicified; cleavage none. That combination decides what it can safely be set into.
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 fossil Ammonite costs
As a guide, fossil Ammonite trades around $10-200 for common polished pairs; large display Madagascan specimens $300-5,000.
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 fossil Ammonite treated, and how?
Commonly acid-etched, air-abraded, polished and resin-repaired; composites assembled from several specimens are routine in the Moroccan trade. LEGAL: fossil export from Morocco technically requires permits under Article 116 of the 2015 Mining Code and is widely unpermitted in practice; Madagascar has periodically suspended fossil export; the UK has voluntary collecting codes at Lyme Regis rather than a ban. Not CITES.
Where does fossil Ammonite come from?
Mahajanga Basin, Madagascar (Cleoniceras, Douvilleiceras), Erfoud and Rissani, Morocco, Lyme Regis and Whitby, England (protected coastline, collection codes apply) and Bearpaw Formation, Alberta, Canada (the ammolite source). Origin affects price, so we name the locality rather than the country on every quote.
Is fossil Ammonite hard enough to wear every day?
Not really. At 3-4 (calcite), higher if silicified 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 fossil Ammonite cost?
Indicatively $10-200 for common polished pairs; large display Madagascan specimens $300-5,000. 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 fossil Ammonite confused with?
Most often Cast resin replicas (extremely common from Morocco), Composite specimens assembled from parts and Carved and 'improved' sutures. A refractive index of 1.486-1.658 and a specific gravity near 2.6-2.9 separate it quickly.
What is fossil Ammonite used for besides jewellery?
mineral collecting, architecture and interiors and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for fossil ammonite?
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 fossil ammonite