Ammonite Fossil
Phenomenal & Rare Gems
An ammonite fossil preserves the coiled, chambered shell of an extinct marine cephalopod rather than a single gem material. The shell or its internal mold may be replaced or filled by different minerals, so color, hardness and surface detail vary with the deposit.
Identity
- Material or variety
- Fossil ammonite shell
- Scientific or material identity
- Mineral-replaced ammonite fossil
- Classification
- Fossil material
- Aliases or trade names
- Snakestone
- Composition or formula
- Mineral composition varies with fossilization
- Crystal system or structure
- Aggregate or composite structure
- Geological or manufacturing origin
- Preserved or mineral-replaced through fossilization.
Origins
Madagascar · Morocco · UK · Germany
Appearance & optical properties
brown stone fossil showing a coiled ammonite spiral.
History & discovery
Ammonites lived in the seas for hundreds of millions of years and disappeared about 66 million years ago. Before their origin was understood, coiled fossils found in England were called snakestones and were sometimes carved with snake heads. Their rapid evolution and wide distribution later made them valuable index fossils for dating rock layers.
Uses & care
- Common uses
- Complete and sectioned fossils are collected, displayed and sometimes polished for ornaments or jewelry. Paleontologists use identifiable ammonite species to compare and date sedimentary rock layers.
- Handling and cleaning
- Handle each fossil according to its preserving mineral and matrix. Dust it with a soft dry brush, support the whole specimen when lifting it, and avoid soaking, acids, ultrasonic cleaning and sudden impacts that may loosen shell or rock layers.
Jewellery
5 pieces of Ammonite Fossil jewellery. Learners earn each one in DigMyGem by learning words; until then it shows as a silhouette.
Spiral of Ages Pendant
Pendant
A polished ammonite coil is held in silver so the chambered spiral faces outward like a turning wheel.
Coiled Coast Brooch
Brooch
A flat ammonite slice shows its inner chambers in pale amber calcite, pinned at the shoulder of a coat.
Jurassic Coil Ring
Ring
A small fossil coil, millions of years old, is set into a signet so the spiral wraps the finger.
Whitby Snakestone
Jewel
A coiled Dactylioceras ammonite, about five centimetres across, from the Yorkshire coast, with a snake's head carved on its open end. In medieval Europe such fossils were taken for snakes turned to stone, the work of saints such as Hilda of Whitby, and traders carved heads on them to sell them as petrified snakes.
Jurassic Spiral Cup
Jewel
An imagined cup made from a polished ammonite shell mounted in silver-gilt, as Renaissance goldsmiths mounted shells.