Ammolite Stone an Iridescent and Valuable Fossil

October 27, 2016

Ammolite Stone an Iridescent and valuable fossil

What is ammolite stone? Value of these iridescent gemstones.  Discover this beautiful Canadian gemstone.

Ammolite is a rare and valuable stone of organic origin, which is obtained from fossilized shells of ammonite (extinct animal in the Upper Cretaceous).



Ammolite has recently entered the market for gemstones.

Korite International Ltd., was the first company mining that began the marketing of ammolite in 1977.

Ammonites have been used for centuries for Indigenous peoples of Southwestern Alberta.  Blackfeet Tribe  use it as an amulet to hunt buffalo and also into their medicine.

Feng Shui practitioners use this "active" gem to detoxify and strengthen the welfare and chi.



The origin of the name came from the word “ammonite”, and ammonite name comes from the word Amun,  (Ancient Egyptian God, this deity was depicted as a ram-headed).


Pliny the Elder called fossils ammonites “animals ammonis cornua” - “horns of Amoon”.


The extinct group of marine mollusc animals (cephalopods), had shells with spiral shape, that resemble rams’ horns. 

Green and Blue Ammolite




Multicolour Ammolite

Ammolite stone is obtained from fossilized shells of Ammonite and is of organic origin.

Due to its structure, consisting primarily on thin sheets stacked of aragonite, ammolite gem displays an IRIDESCENT phenomenon. Thicker plates of aragonite are red and greenish, the most thin and fragile are the blue and violet.


Value of Ammolite

Ammolite displays a beautiful play of colors, the most common are green and red.

The more colors and more iridescence and brightness the ammolite has, the more valuable the stone will be.



The Ammolite Gem is usually cut in freeform cabochon (doublets or triplets).

Usually the back of the doublet is gray - brown shale (original shale of the fossilized ammonite) and the top of a thin thin layer of 0.5 to 0.8 mm thick plates of aragonite, whose brightness and beauty is due to a complicated polished process.

Sometimes we can find an upper layer (triplet), which can be both synthetic spinel, quartz or glass, in order to protect the gem.



These fragile and beautiful gems come from Southern Alberta, Canada. In 2004 was named "official gem" of the province of Alberta.


Occurrence: Sedimentary

As opals, the Canadian Ammolites may show striking patterns that have different names: Lava River, Floral, Ripple, etc ..

These patterns are closely related to the geological layers in which ammonites fossilized are found.

Multicolour Green Blue Yellow Ammolite




Due to its low hardness it is often stabilized with polymers (opticon, lacquer stabilization, resines, etc.). Most ammolite is made into doublets or triplets for use in jewelry.


Because of its fragility (3.5 Mohs), in jewelry, it is more suitable for pendants, earrings and brooches.

As with other gems of organic origin, care must be taken with acid products, perfumes, hairsprays, etc ..





detail of green and blue ammolite

Detail of green and red ammolite

Gemstone of organic origin

Formula  CaCO3  aragonite polymorph (minor amounts of calcite, pyrite, silica, etc.)

  • Crystal system:            Orthorhombic.
  • Hardness (Mohs):         3.5 - 5.5  
  • Fracture:                       Uneven to granular
  • Cleavage:                     None
  • Transparency:              Opaque
  • Lustre:                          Greasy to dull (polish luster - vitreous)
  • Density:                        Average 2.70 g/cm3
  • Refractive index:          1.52 - 1.68
  • Birefringence:               0.135 - 0.145
  • Pleochroism:                None
  • Fluorescence:              Variable (inert to strong yellow)
  • Absorption spectrum:  Not observable
  • Phenomena:                 Iridescence

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