RocksdayLabradorite vs Larvikite
How to tell them apart
A gray plagioclase feldspar that flashes electric blue, green and gold when light hits it at the right angle.
Photo: Parent Géry, Public domain
A dark Norwegian monzonite whose feldspar crystals flash silvery blue.
Photo: Woudloper, Public domain
Quick tests
- Texture: Larvikite is a rock — a mix of grains or minerals; Labradorite is a single mineral.
Key differences
- Labradorite is a single feldspar mineral with stronger flashes.
Side by side
| Property | Labradorite | Larvikite |
|---|---|---|
| Type | Mineral | Igneous rock |
| Mohs hardness | 6–6.5 | 6 |
| Luster | Vitreous | Granular with blue flashes |
| Streak | White | — |
| Colors | Gray, Black, Blue | Gray, Black, Blue |
| Crystal system / structure | Triclinic | Coarse-grained |
| Specific gravity | 2.68–2.72 | 2.6–2.8 |
| Formula | (Ca,Na)(Al,Si)₄O₈ | — |
| Found in | Labrador, Canada; Finland | Larvik, Norway |
Properties that are the same for both are grayed out.
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 →How to identify larvikite
- Dark gray with large feldspar crystals.
- Silver-blue flashes when turned in light.
- Little or no quartz.
Structure: Coarse-grained
Full Larvikite guide →More comparisons
Could you tell them apart from a blurry close-up?
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