RocksdayGneiss vs Migmatite
How to tell them apart
A high-grade metamorphic rock with bold light and dark bands, formed under intense heat and pressure.
Photo: No machine-readable author provided. Siim assumed (based on copyright claims)., CC BY-SA 3.0
A rock that was heated until it partly melted, leaving swirls of light granite in dark gneiss.
Photo: James St. John, CC BY 2.0
Key differences
- Gneiss bands are more regular.
Side by side
| Property | Gneiss | Migmatite |
|---|---|---|
| Type | Metamorphic rock | Metamorphic rock |
| Mohs hardness | 6–7 | 6–7 |
| Luster | Granular | Granular |
| Colors | Gray, White, Black, Pink | Gray, White, Pink, Black |
| Crystal system / structure | Coarse, banded | Swirled, partly melted bands |
| Specific gravity | 2.6–2.9 | 2.6–2.8 |
| Found in | Acasta River, Canada; Outer Hebrides, Scotland | Finland; Scottish Highlands |
Properties that are the same for both are grayed out.
How to identify gneiss
- Alternating light and dark bands, often wavy.
- Coarse, visible grains.
- Hard; doesn't split into sheets.
- Bands may be folded.
Structure: Coarse, banded
Full Gneiss guide →How to identify migmatite
- Swirling, folded light and dark layers.
- Pale granite-like patches and veins.
- Coarse grains.
Structure: Swirled, partly melted bands
Full Migmatite guide →More comparisons
Could you tell them apart from a blurry close-up?
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