Ammolite Doublets Or Triplets | Gemopedia

Ammolite is a gem that comes from the fossilized shell of an extinct, squid-like creature called an ammonite. Found in Canada, the iridescent shell of fossilized ammonites is available as ammonite fossils or in iridescent gems cut from the fossils under the trade name ammolite. Ammolite's iridescent play of color is what makes it so distinctive and attractive. Its iridescence occurs when the fossilized ammonite shell becomes mineralized. Unlike most gems, whose colors come from light absorption, ammolite's iridescent color is caused by interference with the light that gets trapped within stacked layers of thin platelets that make up the fossilized shell. Since the layer of ammolite is typically thin, most ammolite is made into doublets or triplets for use in jewelry. A doublet is a thin slice of shell that is typically covered by a durable material (often crystal, glass or plastic) that both protect the gem and maximize its presentation. Triplets are typically assembled by placing a thin slice of shell between two layers of more durable material that are attached with epoxy. While shades of green and red are usually seen, all spectral colors are possible.
Alternate
Names
Ammonite, Lumachelle, Calcentine
Colors
Gray To Brown With Iridescent Colors

Ammolite Doublets Or Triplets Classification

Common Name

Ammolite Doublets Or Triplets

Species

NA

Variety

Colors

Gray To Brown With Iridescent Colors

Alternate Names

Ammonite, Lumachelle, Calcentine

Gemstone Groups

Key Separations

Appearance, RI

Comments

Fossilized shell of nautilus like creature. Ammolite or calcentine material is from Alberta, Canada.

Ammolite Doublets Or Triplets Optical Properties

Transparency

Opaque

Refractive Index

1.52-1.68
Tolerance:varies

Birefringence

0.155

Optic Character

NA

Optic Sign

NA

Polariscope Reaction

Aggregate (AGG)

Fluorescence

SWUV: Inert to strong yellow
LWUV: Inert to strong yellow

CCF Reaction

Pleochroism

None

Dispersion

Strength: none

Comments

Ammolite Doublets Or Triplets Chemistry & Crystallography

Chemical Name

mostly composed of aragonite or calcite

Chemical Formula

fossilized, mineralized ammonite shell

Synthesis

Crystal System

NA

Classification

Organic

Nature

Natural

Crystallinity

Comments

Ammolite Doublets Or Triplets Characteristic Physical Properties

Hardness

4

Streak

Specific Gravity

2.7-2.8 Typical:2.7

Toughness

Varies

Inclusions

Ammolite or ammonite can be iridescent with mosaic patterns. Due to the nature of the material it is often stabilized with polymers. Well preserved specimens show a nautilus or spiral like appearance. Ammolite is often made into doublets or triplets. Quartz or lab created spinel is used as a dome and the base is typically made of shale, glass or lab created spinel.

Luster

Vitreous

Stability

Fracture

Granular, Uneven

Cleavage

None

Comments

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