Mama's Weekly Rock Facts - Ammolite

Ammolite is gemstone quality fossilized ammonite shells usually placenticeras meeki or placenticeras intercalare species.   Ammolite is a thin and fragile sheet of fossilized material most commonly in Reds and greens because of fragility of other colors such as purples, blues, and yellows.  These later colors are considered rarer and are more desirable as a gemstone.

The stacking layers of aragonite, which causes light interference, create the iridescent play of colors.  The crackling effect is cause by exposure to the elements and sediment compression where the thin Ammolite cracks and flakes.  This crackling appearance leads to the nickname ‘dragon skin’ for its scale like patterns.

Gem quality Ammolite is primarily found along the eastern front of North Americas Rocky Mountains, from Alberta Canada and south to Idaho / Montana in the United States.  Native American tribes in this region have long prized Ammolite.  The Blackfeet tribe call Ammolite “buffalo stone” and believe the amuletic stone aids in hunting buffalo and possesses healing powers.

Mineralogy: 

Ammolite: CaCo₃, aragonite polymorph with small impurities of calcite, pyrite, silica, and others

Mohs scale hardness: 4.5 - 5.5

Luster: greasy to dull

Color: gray to brown matrix with primarily red to green iridescence

Transparency: Opaque

Fracture: Uneven to granular

Specific gravity: 2.60 – 2.85

Index of refraction: 1.52 – 1.68

Cleavage: no true cleavage

Metaphysical Properties:

Stone of luck, general healing; detoxify the body, and improve energy flow

Image from Wikipedia

by Amanda Rice