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 a striking Polymorphites golden pyrite ammonite fossil, collected from the famous Black Ven Marls at Stonebarrow Cliff, Charmouth, part of the world-renowned Jurassic Coast at Lyme Regis, Dorset, UK. This is a carefully chosen natural specimen, and the photographs show the exact fossil you will receive, with full sizing clearly visible in the images.

This fossil includes a lifetime Certificate of Authenticity on a generic card, guaranteeing 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, within the Family Polymorphitidae. These ammonites lived during the Sinemurian Stage, approximately 195 million years ago, when warm, shallow seas covered much of southern Britain.

Polymorphites is particularly valued for its robust shell form and evolutionary importance within Early Jurassic ammonite lineages. Specimens from Dorset are highly sought after due to their excellent preservation and their significance in British Jurassic stratigraphy.

Morphology and Diagnostic Features

This specimen displays the defining characteristics of Polymorphites, including:

• A strong, moderately evolute shell with clear symmetry
• Bold, well-developed radial ribs across the flanks
• A rounded whorl section giving a robust appearance
• Distinct growth lines reflecting natural shell development

Polymorphites ammonites are prized for their substantial form and attractive ribbing, making them excellent display fossils as well as scientifically informative specimens.

Golden Pyrite Preservation

One of the most impressive features of this fossil is its natural golden pyrite mineralisation. Pyrite, often called “fool’s gold,” formed when iron and sulphur combined under low-oxygen conditions within the fine marine sediments of the Jurassic seabed. Over millions of years, this process replaced or infilled the original shell material, preserving delicate surface detail while creating a shimmering metallic gold finish.

Golden pyrite ammonites from the Black Ven Marls are especially sought after because they combine outstanding scientific value with exceptional aesthetic appeal. The reflective pyrite enhances the ribbing and shell contours, making this specimen a standout display piece.

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 under conditions favourable for pyrite formation.

Stonebarrow Cliff and Charmouth lie within 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 continue to play a vital role in 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 attracted to pyrite preservation
• Educational and teaching collections
• Display cabinets and curated fossil shelves

The combination of robust shell form, bold ribbing, 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 celebrated fossil localities.