Peritektoisia
Peritektoisia is a term derived from Finnish and refers to a specific geological phenomenon. It describes a type of intrusive igneous rock formation where a magma chamber cools and solidifies in a way that creates a distinctive texture. This texture is characterized by the presence of larger, euhedral or subhedral crystals (crystals with well-defined faces) that are surrounded by a finer-grained groundmass. These larger crystals are known as phenocrysts, and the finer-grained material is the matrix.
The formation of peritektoisia textures is often attributed to a two-stage cooling process. Initially, some mineral
Geologists use the presence of peritektoisia textures to infer aspects of a magmatic body's emplacement history