metamorphic
Migmatite
Migmatite (Mixed Rock)
Hardness: 6-7 on Mohs scale. Color: Greenish-grey, black, and white swirls. Luster: Dull to vitreous. Structure: Gneissic banding with evidence of partial melting (ptygmatic folds).
- Hardness
- 6-7 on Mohs scale
- Color
- Greenish-grey, black, and white swirls
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Greenish-grey, black, and white swirls. Luster: Dull to vitreous. Structure: Gneissic banding with evidence of partial melting (ptygmatic folds).
Formation & geological history
Formed at the boundary of metamorphism and melting (ultra-metamorphism). These rocks represent the transition from metamorphic to igneous rocks under extreme heat and pressure, often occuring in Precambrian shield areas.
Uses & applications
Primarily used as decorative building stone, countertops, and flooring due to its high durability and unique aesthetic patterns. Also used as crushed stone in construction.
Geological facts
The word migmatite comes from the Greek word 'migma', meaning 'mixture'. It consists of a darker metamorphic part (melanosome) and a lighter igneous part (leucosome) that crystallized from partial melt.
Field identification & locations
Identify in the field by looking for 'swirly' or folded light-colored granitic veins mixed with darker, foliated metamorphic rock. Common in the Canadian Shield, Scandinavia, and the Scottish Highlands.
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