Migmatite

Migmatite

Migmatite

This rock sample displays tightly folded biotite schist that is offset and intruded by an light-colorded aplite dike (quartz and feldspar). Rocks like this are common in rocks that formed along the margins of an igneous intrusion near where the rocks were approachin their melting point at depth.
https://gotbooks.miracosta.edu/rocks/metamorphic/25.html 2/2/2021