Ammonite

Calcite lined halves and matched pairs from Madagascar, Lower Jurassic Promicroceras clusters, and shells carrying opalescent nacre.

Buy Ammonite Fossils by Species, Age and Preparation

An ammonite is the coiled external shell of an extinct marine cephalopod, divided internally by septa into gas filled chambers and preserved when mineral replaced the original aragonite. Buy from the 6 ammonites catalogued on this page and each shell carries a stated geological age, a country of origin, and the preparation it received on the bench before listing. Astro Gallery of Gems takes ammonite material directly from the collectors working the Madagascan and Moroccan beds, has it prepared under magnification, and writes any restoration into the description instead of leaving a buyer to discover it.

Species, Age and the Beds They Came Out Of

Ammonites ran from roughly 240 million years ago to the close of the Cretaceous, and where a shell sat in that span shapes its ornament, its size and its price. The four groups below account for what reaches this page.

Preservation Sets the Price Before Diameter Does

Two ammonites of identical width can sit a long way apart on price, and preservation explains almost all of that gap. Astro Gallery grades incoming shells by what replaced the aragonite first and by size second.

Shop Ammonites at the Figures Showing Now

Each line below is a single catalogued specimen with its own weight and dimensions. Figures update from stock as pieces move, so a shell that sells clears out of the table rather than sitting there as something no buyer can add to the cart.

Sutures, Ribbing and the Keel Identify a Shell

Where each internal septum met the outer wall it left a fluted line, and that suture is the single most reliable identifier a fossil ammonite carries. Simple zigzag goniatitic sutures mark the oldest Palaeozoic forms, ceratitic sutures with frilled valleys follow in the Triassic, and the fern like ammonitic sutures of the Jurassic and Cretaceous divide and subdivide across the whorl. Rib count, rib branching, the presence or absence of a raised keel along the outer edge, and the width of the umbilicus complete the picture. A description that names a genus without showing sutures or ribbing is describing a shape rather than a species.

Preparation and Restoration Declared Before You Buy

Almost every ammonite offered anywhere has been worked on, and the honest question is which work and how much. These four points cover what separates a prepared specimen from a rebuilt one.

Order a Polished Half, a Matched Pair or a Full Round Shell

Buyers split cleanly into two camps here, and the split has more to do with what a specimen is for than with what it costs. Astro Gallery prices both routes on preservation and preparation rather than on diameter alone.

Terms an Ammonite Description Uses

Display, Teaching and Gifting a Fossil Shell

An ammonite works harder in a room than most fossils because the spiral reads from any angle. Interior buyers stand a lapped half on a stack of books or hang a large matrix plate as wall relief, and a pair placed with the cut faces outward doubles the pattern across a console. Teachers and parents buy the small boxed pairs by the handful, since a chambered half explains buoyancy, extinction and deep time faster than a diagram does. Collectors chase genus, locality and the quality of the preparation instead.

The spiral also carries a long metaphysical and feng shui vocabulary, described as a stone of change, of prosperity or of grounding, and buyers arrive using those words. Astro Gallery documents species, age, locality, weight and preparation on each ammonite and makes no health, healing or energetic claim about any specimen.

Pyrite Decay, Damp and Keeping a Shell Stable

Fossil shells fail from humidity rather than handling. Pyritised ammonites oxidise in damp air, producing iron sulphate and sulphuric acid that swell, crack and eventually powder a specimen, so keep those pieces below roughly fifty percent relative humidity and add a silica gel sachet to a closed display case. Nacreous shells lose iridescence when they dry too fast or sit in direct sun, and they should never be washed. Dust every ammonite with a dry soft brush along the ribbing, and keep water, ultrasonic tanks and household sprays away from calcite chambers and consolidated shell alike. Support a heavy matrix plate along its full length, because these split on the bedding plane if they flex.

Paying for a Fossil and How It Reaches You

Checkout settles through Shop Pay, PayPal, Apple Pay, Google Pay or a Visa, Mastercard, Discover or Diners Club card, and the listed figure is what the card is charged. Astro Gallery of Gems has sold fossils under its own invoice since 1961, and that itemised invoice names the species where identified, the age, the locality, the weight and any restoration. Specimens are wrapped so no pressure reaches an exposed suture face, blocked into a fitted carton, and double boxed above a pound, then sent tracked and insured with import paperwork attached. The returns policy and the guarantee on about us cover each of those steps.

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Ammonite Questions Answered Before Purchase

Ammonites Beside the Rest of the Natural History Catalogue

Ammonites sit inside a much wider fossil catalogue, so the deciding question is whether the spiral itself or the deep time story matters more to you. Collectors following cephalopods move across to other marine material, while buyers wanting age alone find it in teeth, wood and meteorite iron.