Ammolite
Ammolite is biogenic gem (iridescent fossil aragonite), CaCO3 (aragonite) with trace Fe, Mn. In the hand, it rates 3.5 to 4.5 on the Mohs scale, and it runs blazing red-green iridescence and full-spectrum 'dragon skin'. Premium gem; vivid multi-color and blue material climbs steeply.
The geology.
Ammolite carries the formula CaCO3 (aragonite) with trace Fe, Mn. It belongs to the orthorhombic (aragonite shell layers) system. Its listing category is biogenic gem (iridescent fossil aragonite).
It sits at 3.5 to 4.5 on the Mohs scale. The surface reads greasy to vitreous with intense iridescence. Light behaviour is opaque (iridescent surface layer). Specific gravity runs 2.6 to 2.85. The streak is white to pale yellow. It breaks with flaky; shell layer fractures unevenly, usually stabilized.
Stained-glass fire in crackled 'dragon skin' patches over a fossil ammonite shell, nacreous aragonite aged 70 million years until it flashes every color; almost all gem material wears a protective quartz cap.
It turns up mostly as triplet cabochons, whole iridescent ammonites, jewelry or freeform shell fragments.
The origins.
Bearpaw Formation along the St. Mary River, southern Alberta, Canada, commercially mined nowhere else on Earth.
On value, the database notes: premium gem; vivid multi-color and blue material climbs steeply.
Traditional associations.
In energy work traditions, ammolite is prized as a prosperity and life-force stone, its spiral origin linked to flowing energy.
This is lore, and we label it as lore. The measurable facts are further up the page.
Spotting the real thing.
Stained-glass fire in crackled 'dragon skin' patches over a fossil ammonite shell, nacreous aragonite aged 70 million years until it flashes every color; almost all gem material wears a protective quartz cap.
Nearly all jewelry ammolite is a stabilized doublet or triplet, standard practice, but 'solid natural' claims deserve a side-view; dyed abalone occasionally poses as it.
| Looks like | How to tell them apart |
|---|---|
| Labradorite | Labradorite's flash rolls within a solid feldspar; ammolite's fire sits in a thin crackled shell layer |
| Black opal | Opal's play-of-color floats in patches inside the stone, no fossil shell structure |
| Abalone shell | Abalone is modern nacre, pastel sheen, flexible-feeling curves, no crackle pattern |
At-home tests.
A loupe and a window seat settle most questions about ammolite. No workshop required.
| Test | What you should see |
|---|---|
| Loupe | tessellated crack pattern ('dragon skin') in the color layer |
| Side view of cabs | triplet sandwich (shale base, ammolite, quartz cap) |
| By eye | Soft and flaky if unstabilized, untreated rough is fragile |
Destructive tests belong to a gemologist, not a kitchen table. If a piece matters to you, pay for an appraisal before you take a file to it.
Care & handling.
At 3.5 to 4.5 on the Mohs scale this is a soft material. Keep it as a display piece, store it apart from harder stones, and skip daily-wear settings.
It breaks with flaky; shell layer fractures unevenly, usually stabilized, which is worth knowing before you set it or drop it.
Clean it by hand, dry it properly, and keep it away from ultrasonic cleaners and hot steam.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is CaCO3 (aragonite) with trace Fe, Mn. Crystal system: Orthorhombic (aragonite shell layers). Specific gravity: 2.6 to 2.85. Streak: White to pale yellow. Cleavage and fracture: Flaky; shell layer fractures unevenly, usually stabilized.
How it reaches the market
Bearpaw Formation along the St. Mary River, southern Alberta, Canada, commercially mined nowhere else on Earth.
What it gets confused with
Labradorite: Labradorite's flash rolls within a solid feldspar; ammolite's fire sits in a thin crackled shell layer. Black opal: Opal's play-of-color floats in patches inside the stone, no fossil shell structure. Abalone shell: Abalone is modern nacre, pastel sheen, flexible-feeling curves, no crackle pattern.
What it is worth
Premium gem; vivid multi-color and blue material climbs steeply.
Where buyers get caught
Nearly all jewelry ammolite is a stabilized doublet or triplet, standard practice, but 'solid natural' claims deserve a side-view; dyed abalone occasionally poses as it.
One more thing
Ammolite is one of the few official organic gemstones (recognized 1981) and the Blackfoot people knew it long before as iniskim, 'buffalo stone', a luck talisman said to call the herds.
An education-first guide.
We do not stock ammolite. Writing it up regardless is the point of a reference library.
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