This term describes a microscopic rock texture characterized by the worm-like, intricate intergrowth of two or more minerals. It typically forms when a single high-temperature mineral breaks down into a stable mixture as the rock cools or undergoes metamorphism. Geologists look for this texture in thin sections to understand the pressure and temperature history of the rock.
Heard on the job
The thin section shows a strongly symplectitic texture around the garnet margins, indicating rapid decompression.