Promicroceras Pyrite Ammonite Fossil Lyme Regis Dorset UK Lower Lias Jurassic Coast Golden Pyrite Rare Display Specimen Authentic

Description

Promicroceras Golden Pyrite Ammonite Fossil – Jurassic Coast, Dorset, UK

This stunning Promicroceras ammonite fossil is beautifully preserved with natural golden pyrite, originating from the Black Ven Marls of the Lower Lias at Stonebarrow Cliff, Charmouth, near Lyme Regis, Dorset, UK. The metallic lustre of pyrite enhances the intricate structure of the ammonite, creating a visually striking specimen that combines scientific importance with exceptional display appeal. The fossil shown in the photographs is the exact piece you will receive, carefully selected for its quality and preservation.

Geological Age & Formation

This ammonite dates to the Early Jurassic period, specifically the Sinemurian stage, approximately 190–199 million years ago. The Black Ven Marls are world-renowned for their fossil-rich deposits, formed in a shallow marine environment where fine sediments accumulated and preserved marine life in remarkable detail. Promicroceras is strongly associated with the Promicroceras planicosta Biozone, a key stratigraphic marker used to identify specific horizons within the Lower Lias.

Taxonomy & Classification

• Order: Ammonitida
• Superfamily: Psiloceratoidea
• Family: Arietitidae
• Genus: Promicroceras

Promicroceras is one of the most recognisable ammonites from the Lower Jurassic and was first described by Hyatt. It represents an important stage in ammonite evolution following the end-Triassic extinction event.

Morphology & Golden Pyrite Preservation

This specimen displays the classic planispiral coiling of ammonites, with clearly defined whorls and strong ribbing radiating across the shell. The ribs are typically fine to moderately pronounced and may strengthen toward the outer whorls, giving the fossil a textured and dynamic appearance.

The standout feature of this specimen is its golden pyrite preservation. Pyritisation occurs when iron sulphide replaces the original shell material under low-oxygen conditions, producing a metallic, gold-like sheen. This process not only enhances the fossil’s aesthetic appeal but also highlights fine structural details, making each ammonite unique.

The contrast between the dark matrix of the Black Ven Marls and the shimmering pyrite ammonite creates a striking natural display, highly sought after by collectors.

Depositional Environment

The Black Ven Marls were deposited in a relatively low-energy marine setting, where fine sediments settled on the seabed. Periodic anoxic conditions facilitated the preservation of organic material and allowed mineral replacement processes such as pyritisation to occur. These conditions were ideal for preserving ammonites like Promicroceras in exceptional detail.

The Jurassic seas in this region supported a diverse ecosystem, including ammonites, belemnites, bivalves, and marine reptiles, with Promicroceras playing an important role as a free-swimming cephalopod.

Preparation & Presentation

This fossil has been carefully prepared to reveal the full detail of the ammonite while preserving its natural matrix. The preparation enhances the visibility of the pyrite and shell structure, ensuring the specimen is both stable and visually impressive.

Authenticity & Provenance

This is a genuine Promicroceras ammonite fossil and includes a Certificate of Authenticity with a lifetime guarantee. All specimens are responsibly sourced and professionally prepared, ensuring confidence in both authenticity and geological provenance.

Display & Collectability

Golden pyrite ammonites from Lyme Regis are highly desirable due to their rarity and striking appearance. This specimen is ideal for collectors, educators, or as a standout decorative piece. Its origin from the Jurassic Coast, a UNESCO World Heritage Site, adds further historical and scientific significance.

Condition & Sizing

Please refer to the photographs for full sizing and condition details, as they form part of the description. The fossil is a carefully chosen piece, and the images accurately represent the exact specimen you will receive.