Migmatite is a composite rock formed under high-grade metamorphic conditions where partial melting occurs, creating distinct layers of light-colored granitic material and dark metamorphic rock. It displays a characteristic swirling or banded appearance known as migmatitic structure, often seen in high-grade regional metamorphic terrains. Collectors usually look for decorative polished slabs that highlight the complex interplay of light and dark mineral veins.
Is this migmatite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch migmatite with a known reference. Migmatite sits at Mohs 5-7, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Texture: Distinctive banding and folds.
- 3Pick out the mineralsComposition: Light leucosome and darker melanosome with remnants of the original rock. Identify the two or three most abundant grains.
- 4Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 5Match the color rangeCompare against the expected color range: black, white, gray, pink.
Often confused with
Migmatite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside migmatite
Minerals reported to co-occur with migmatite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 5-7
- Density
- 2.6-2.9 g/cm³
- Luster
- Vitreous
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Decorative, Construction, Architectural
- Host rock
- deep crustal metamorphic zones
- Texture
- Distinctive banding and folds
- Composition
- Light leucosome and darker melanosome with remnants of the original rock
Where rockhounds find migmatite
Classic worldwide localities
- Finland
- Canada
- Norway
- Scotland
- United States
Field-hunting tip
Where it forms: deep crustal metamorphic zones. If you start seeing quartz, feldspar, biotite in float, you are in the right ground.
Common questions
How do you identify migmatite?+
Where is migmatite found?+
What rocks look like migmatite?+
What minerals are found with migmatite?+
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Find migmatite on the map
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