RocksdayAmmolite vs Labradorite
How to tell them apart
A rare gem made from the shimmering shell layers of fossil ammonites.
Photo: James St. John, CC BY 2.0
A gray plagioclase feldspar that flashes electric blue, green and gold when light hits it at the right angle.
Photo: Parent Géry, Public domain
Quick tests
- Scratch glass: Labradorite scratches glass (Mohs 6–6.5); Ammolite can't (Mohs 3.5–4.5).
- Texture: Ammolite is a fossil; Labradorite is a single mineral.
Key differences
- Labradorite flashes on a feldspar cleavage plane.
Side by side
| Property | Ammolite | Labradorite |
|---|---|---|
| Type | Fossil | Mineral |
| Mohs hardness | 3.5–4.5 | 6–6.5 |
| Luster | Vitreous, iridescent | Vitreous |
| Streak | — | White |
| Colors | Red, Green, Orange, Blue | Gray, Black, Blue |
| Crystal system / structure | Iridescent ammonite shell (aragonite) | Triclinic |
| Specific gravity | 2.6–2.85 | 2.68–2.72 |
| Formula | — | (Ca,Na)(Al,Si)₄O₈ |
| Found in | Southern Alberta, Canada | Labrador, Canada; Finland |
Properties that are the same for both are grayed out.
How to identify ammolite
- Vivid rainbow iridescence in patches.
- Cracked 'dragon-skin' mosaic pattern.
- Usually thin and backed on shale.
Structure: Iridescent ammonite shell (aragonite)
Full Ammolite guide →How to identify labradorite
- Dull gray until tilted — then a vivid blue/green flash.
- Fine parallel lines on cleavage faces.
- Hardness about 6.
- Flash only appears from one direction.
Crystal system: Triclinic
Full Labradorite guide →More comparisons
Could you tell them apart from a blurry close-up?
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