Description
Genuine Golden Pyrite Tropidoceras Ammonite from the Jurassic Coast
Offered here is a superb Tropidoceras golden pyrite ammonite fossil, collected from the famous Black Ven Marls at Stonebarrow Cliff, Charmouth, on the iconic Jurassic Coast at Lyme Regis, Dorset, UK. This is a carefully chosen, naturally preserved specimen, with the photographs showing the exact fossil you will receive. Full sizing and scale are clearly visible in the images.
The fossil was discovered by our own team members, Alister and Alison, on 22 January 2026, and has been professionally cleaned, prepared, and treated by Alison to ensure long-term stability and excellent visual presentation. A lifetime Certificate of Authenticity on a generic card is included, guaranteeing the specimen as a genuine fossil.
Species Overview – Tropidoceras
Tropidoceras is a distinctive ammonite genus from the Lower Jurassic (Lower Lias), belonging to the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Eoderoceratidae. These ammonites lived during the Sinemurian Stage, approximately 195 million years ago, when shallow seas covered much of what is now southern England.
Tropidoceras is well known for its elegant shell form and strong keel, and it is an important genus used in Lower Jurassic biostratigraphy. Specimens from the Dorset coast are especially valued due to their scientific significance and high-quality preservation.
Morphology and Diagnostic Features
This specimen displays the classic characteristics that define Tropidoceras, including:
- A moderately compressed shell with clear symmetry
- A strong, continuous ventral keel running along the outer edge
- Well-defined ribbing across the flanks
- Clear growth lines that reflect natural shell development
The pronounced keel is thought to have improved hydrodynamics, suggesting Tropidoceras was an active swimmer within the Jurassic marine ecosystem.
Golden Pyrite Preservation
One of the most striking features of this ammonite is its natural golden pyrite mineralisation. Pyrite formed when iron and sulphur combined under low-oxygen conditions within the marine sediments of the Jurassic seabed. Over millions of years, this process replaced or infilled the original shell material, preserving fine surface detail while giving the fossil its distinctive metallic gold appearance.
Golden pyrite ammonites from the Black Ven Marls are particularly sought after by collectors, as they combine exceptional scientific value with outstanding aesthetic appeal. The reflective surface highlights the ribbing and keel, making this specimen a standout display fossil.
Geological Context – Black Ven Marls, Lower Lias
The Black Ven Marls were deposited in a quiet offshore marine environment during the Early Jurassic. Fine-grained muds accumulated on the sea floor, allowing ammonites and other marine organisms to be rapidly buried and fossilised.
Stonebarrow Cliff and Charmouth form part of the UNESCO World Heritage-listed Jurassic Coast, one of the most important fossil regions in the world. Fossils from this area have been collected and studied for over two centuries and continue to play a crucial role in understanding Jurassic marine life and evolution.
Collector, Educational, and Display Value
Tropidoceras ammonites are highly desirable for:
- Fossil and ammonite collectors
- Mineral collectors attracted to pyrite preservation
- Educational and teaching collections
- Display cabinets and curated fossil displays
The combination of elegant shell form, strong keel, and golden pyrite mineralisation makes this specimen both visually impressive and scientifically meaningful.
Provenance and Authenticity
- Fossil: Tropidoceras golden pyrite ammonite
- Formation: Black Ven Marls, Lower Lias
- Geological age: Lower Jurassic, Sinemurian Stage
- Locality: Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK
- Discovered: 22 January 2026 by Alister and Alison
- Prepared by: Alison
- Certificate: Lifetime Certificate of Authenticity included
This fossil represents a genuine piece of Dorset’s Jurassic seabed, preserving a marine animal that lived nearly 200 million years ago, and offers a rare opportunity to own a beautifully preserved golden pyrite ammonite from one of the world’s most celebrated fossil localities.
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