The key difference between ammonite and ammolite is that ammonite is a shelled cephalopod that became extinct about 66 million years ago, while ammolite is an opal-like organic gemstone.
Ammonites are extinct organisms found as fossils. On the other hand, ammolite is a gemstone that comes from ammonites. If a fossil exists inside a glossy shell, it is still called an ammonite fossil. When there is no fossil, it is called an ammolite. Moreover, an ammonite must be buried deep under the sea without oxygen and heat to become an ammolite gem.
CONTENTS
1. Overview and Key Difference
2. What is Ammonite
3. What is an Ammolite
4. Similarities – Ammonite and Ammolite
5. Ammonite vs Ammolite in Tabular Form
6. Summary – Ammonite vs Ammolite
What is an Ammonite?
Ammonite was a shelled cephalopod that died out about 66 million years ago. Fossils of ammonites are found all over the world, sometimes in very large concentrations. Ammonites are a group of extinct marine mollusc animals in the sub-class of Ammonoidea of the class Cephalopoda. The class Cephalopoda is divided into three subgroups, including coleoids, nautiloids, and ammonites. The earliest species of ammonites appeared during the Devonian geologic period, and the last species either vanished in the Creataceous-Paleogene extinction event or during the Danian epoch of Plaleocene geological period. Ammonites are excellent index fossils. Their fossil shells typically take the form of planispirals. However, helically spiralled and non-spiralled forms also have been found.
Figure 01: Ammonite
Ammonites have earned their nickname snakestones due to their structure and shape, although they are not reptiles. Ammonites were born with tiny shells, and as they grew, they built new chambers onto the shell. They came in a range of sizes. Some of them were only a few millimetres, and others were very large in size. Larger sized ammonites appeared from the late Jurassic period onwards. Moreover, many ammonites probably lived in the open water of ancient seas. Furthermore, larger species of ammonites would have eaten crustaceans, bivalves, and fish, while smaller species would probably have eaten plankton.
What is an Ammolite?
Ammolite is an opal-like organic gemstone normally found on the eastern slopes of the Rocky Mountains of North America. It is normally made up of fossilized shells of ammonites. Ammolites are composed of a mineral called aragonite, the same mineral contained in nacre (mother pearl). It is one of the few biogenic gemstones. Other biogenic gemstones include amber and pearl.
Figure 02: Ammolite
In 1981, ammolite was given the official gemstone status by the World Jewellery Confederation (CIBJO). The commercial mining of ammolites was started the same year. It was designated as the official gemstone of the City of Lethbridge, Alberta, in 2007. Moreover, Marcel Charbonneau and Mike Berisoff were the first to create doublets of ammonite gem in 1967.
What are the Similarities Between Ammonite and Ammolite?
- The coating of some ammonites changes because of chemical reactions, thus forming ammolites gemstone.
- Ammolite is the trade name for the nacreous layer of the shell of the fossils of ammonites.
- Both have specific importance to scientists and traders.
- Both can be found in the area bordering the Canadian Rocky Mountains.
What is the Difference Between Ammonite and Ammolite?
Ammonite was a shelled cephalopod that became extinct about 66 million years ago, while ammolite is an opal-like organic gemstone normally found in the eastern slopes of the Rocky Mountains of North America. Thus, this is the key difference between ammonite and ammolite.
The below infographic presents the differences between ammonite and ammolite in tabular form for side by side comparison.
Summary – Ammonite vs Ammolite
Ammonites are extinct organisms that are found as fossils. Ammolite is a gemstone that comes from ammonites. Ammonites have to be buried deep under the sea without oxygen and heat to become ammolite organic gemstones. So, this is the key difference between ammonite and ammolite.
Reference:
1. “Ammonoid.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.
2. “About Ammolite.” Ammolite Museum.
Image Courtesy:
1. “Ammonite-petrification-fossil-snail” (CC0) via Pixabay
2. “Ammolite from Placenticeras fossil ammonite (Bearpaw Formation, Upper Cretaceous, 70-75 Ma; mine in St. Mary River Valley, Alberta, Canada) 13 (40630260954)” By James St. John (CC BY 2.0) via Commons Wikimedia