Migmatite

Migmatite is a composite rock formed when high-grade metamorphic rock partially melts. It preserves interlayered metamorphic material and melt-derived igneous material.

Anatexis: The partial melting of pre-existing rocks, commonly during high-grade metamorphism. Anatexis produces the melt that forms migmatite’s igneous component.
Metamorphic rock: Rock transformed in the solid state by changes in temperature, pressure, or chemically active fluids. Migmatite retains metamorphic rock alongside material crystallized from melt.
Partial melting: The melting of only some minerals or components in a rock, leaving a solid residue. Migmatite is a field-scale record of partial melting in the crust.
Metatexite: A migmatite in which the original metamorphic structure remains largely recognizable. Metatexite is the less thoroughly reorganized structural form of migmatite.
Leucosome: The pale, melt-derived part of a migmatite, typically enriched in quartz and feldspar. Leucosome layers record where melt crystallized or accumulated.
Igneous rock: Rock formed when molten material cools and crystallizes. Migmatite’s pale layers can crystallize from melt within metamorphic rock.
Granite: A coarse-grained felsic igneous rock composed mainly of quartz and feldspar. Migmatites can preserve melt-derived material compositionally similar to granite.
Diatexite: A migmatite in which extensive melting has largely obscured the original metamorphic structure. Diatexite contrasts with migmatite whose inherited structure remains prominent.
Melanosome: The dark, residue-rich part of a migmatite left after partial melting and melt extraction. Melanosome preserves the refractory minerals beside migmatite’s melt-derived layers.
Gneiss: A coarse-grained metamorphic rock with compositional or mineral banding. Gneiss is a common host whose banding may be overprinted by partial melting.

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