Polymorphites Golden Pyrite Ammonite Fossil Jurassic Dorset UK Black Ven Marls Lower Lias Stonebarrow Cliff Charmouth Lyme Regis

Description

Genuine Golden Pyrite Polymorphites Ammonite from the Jurassic Coast

Offered here is an impressive Polymorphites golden pyrite ammonite fossil, collected from the renowned Black Ven Marls at Stonebarrow Cliff, Charmouth, part of the internationally celebrated Jurassic Coast at Lyme Regis, Dorset, UK. This is a carefully chosen natural specimen, with photographs showing the exact fossil you will receive. Full sizing and scale can be clearly seen in the images provided.

This fossil includes a lifetime Certificate of Authenticity on a generic card, confirming it as a genuine natural specimen. The ammonite has been professionally cleaned, prepared, and stabilised to enhance detail while preserving its original geological character.

Fossil Type and Species – Polymorphites

Polymorphites is a classic ammonite genus from the Lower Jurassic (Lower Lias), belonging to the Order Ammonitida and Family Polymorphitidae. These ammonites lived during the Sinemurian Stage, approximately 195 million years ago, when warm, shallow epicontinental seas covered much of what is now southern Britain.

Polymorphites is well known for its robust shell form and evolutionary importance within Early Jurassic ammonite lineages. Specimens from Dorset are particularly sought after due to their strong preservation and long history of scientific study.

Morphology and Diagnostic Characteristics

This specimen displays the defining features of Polymorphites, including:

• A robust, moderately evolute shell, with earlier whorls visible
• Bold, well-developed radial ribbing across the flanks
• A broad, rounded whorl section giving a powerful appearance
• Clear growth lines reflecting natural shell development

The thick shell and pronounced ribbing give Polymorphites a distinctive and substantial look, making it an excellent fossil for both display and comparative study.

Golden Pyrite Preservation

One of the most visually striking aspects of this fossil is its natural golden pyrite mineralisation. Pyrite formed when iron and sulphur combined under low-oxygen conditions within the fine marine sediments of the Jurassic seabed. Over millions of years, pyrite replaced or infilled the original shell material, preserving fine surface detail while producing a shimmering metallic gold finish.

Golden pyrite ammonites from the Black Ven Marls are especially prized because they combine strong scientific value with exceptional aesthetic appeal. The reflective surface enhances the ribbing and shell contours, making this specimen particularly eye-catching under display lighting.

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 settled on the sea floor, allowing ammonites and other marine organisms to be rapidly buried and fossilised under conditions favourable for mineral replacement.

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 locality have been collected and studied for over two centuries and remain central to understanding Jurassic marine ecosystems, sedimentology, and ammonite evolution.

Collector, Educational, and Display Value

Polymorphites ammonites are highly desirable for:

• Fossil and ammonite collectors
• Mineral collectors drawn to pyrite preservation
• Educational and teaching collections
• Display cabinets and curated fossil shelves

The combination of robust shell form and golden pyrite mineralisation makes this specimen both visually impressive and scientifically meaningful.

Authenticity and Provenance

• Fossil type: Polymorphites ammonite
• Preservation: natural golden pyrite
• Formation: Black Ven Marls, Lower Lias
• Geological age: Lower Jurassic, Sinemurian Stage
• Locality: Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK
• 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 iconic fossil localities.