Ammonite Shell

saf-ahyuh r

Ammonites were marine animals that existed during the Jurassic and Cretaceous periods, and are related to modern-day octopi, squid and cuttlefish. The same event that wiped out dinosaurs was the end of this species, as well. On rare occasions, the ammonite fossilized shells became mineralized, exhibiting a striking iridescent play of color. Ammonite is typically found as fossil specimens or as iridescent gems cut from the fossils under the trade name Ammolite.

Ammonite Shell Polished
Ammonite Shell Classification
Common Name Ammonite Shell
Species Fossil
Ammonite Shell Optical Properties
Transparency Opaque
Refractive Index 1.520-1.680
Tolerance:varies
Birefringence 0.155
Optic Character NA
Optic Sign NA
Polariscope Reaction Aggregate (AGG)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism None
Ammonite Shell Characteristic Physical Properties
Hardness 3.5-4.0
Specific Gravity 2.750-2.800 Typical:2.700
Toughness Varies
Inclusions Well preserved specimens show nautilus or spiral like appearance. Rare specimens display iridescence with mosaic patterns. Due the nature of the material it is often stabilized with polymers.
Luster Vitreous, Dull
Stability Poor
Fracture Granular, Uneven
Cleavage None
Ammonite Shell Chemistry & Crystallography
Chemical Name Primarily aragonite or calcite; may also contain pyrite, silica and other materials
Chemical Formula fossilized ammonite shell
Crystal System NA
Chemistry Classification Organic

Ammonite Shell Colors

  • Multi-color Ammonite Shell Multi-color
  • Brown Ammonite Shell Brown
  • Black Ammonite Shell Black

Alternate Names

Ammolite, Ammonite, Korite, Aapaok And Calcentine

Countries of Origin

Canada; United States of America (the); Morocco; Russian Federation (the); Madagascar; Peru

History

When dinosaurs roamed the earth, ammonites lived in the sea. They are related to modern-day octopi, squid and cuttlefish. The same event that wiped out dinosaurs marked the end of this species as well. On rare occasions, the ammonite fossilized shells became mineralized, exhibiting a striking iridescent play of color. A creature of the Jurassic and Cretaceous periods, ammonite today is typically found as fossil specimens or as iridescent gems cut from fossils and marketed under the trade name Ammolite.

Shop Ammonite Shell

Related Videos

Sisk Gemology Reference

Showcasing 200 gemstones in over 1,000 pages and accompanied by more than 2,000 photos, The Sisk Gemology Reference is a must-have in every collector’s library. Each comprehensive, three-volume set features state-of-the-art photography, detailed illustrations, and scientifically precise descriptions to create an entrancing experience for gemstone amateurs and afficionados alike.

Shop Now

 

Species/Variety

Pyritized Ammonite

Ammonites were marine animals that existed during the Jurassic and Cretaceous periods, and are related to modern-day octopi, squid and cuttlefish. The same event that wiped out dinosaurs was the end of this species, as well. Pyritized ammonite occurs when, during petrification, the ammonite's organic material is replaced with pyrite, or iron disulfide more commonly known as 'fool's gold'. The result is a beautifully preserved and durable ammonite fossil.

Pyritized Ammonite Ammonite Shell
Pyritized Ammonite Classification
Common Name Pyritized Ammonite
Pyritized Ammonite Optical Properties
Refractive Index 1.81
Pyritized Ammonite Characteristic Physical properties
Specific Gravity 4.9
Inclusions pyritized ammonite is fossil ammonite that has been replaced by pyrite. Well preserved specimens show nautilus or spiral like appearance.
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.