endurmyndun

Endurmyndun is the geological process by which existing rocks or minerals undergo physical and chemical changes to form new mineral assemblages and textures. The term combines endur-, meaning again or anew, with myndun, meaning formation. In petrology, endurmyndun is primarily associated with metamorphism, a set of processes driven by variations in temperature, pressure and the presence of chemically active fluids.

The mechanisms of endurmyndun include recrystallization, where minerals grow into new grains without melting, mineral phase changes under different thermodynamic conditions, and metasomatism, where fluids alter the chemical composition of rocks to form new minerals. Deformation during metamorphism can produce preferred orientations of minerals, known as foliation or lineation, and develop banded or layered textures such as schistosity or gneissic layering. The textural and mineralogical changes reflect the pressure–temperature history of a rock.

Endurmyndun occurs in several settings: regional metamorphism associated with large-scale tectonic forces, contact metamorphism adjacent to intruding magma bodies, and hydrothermal or metasomatic metamorphism driven by hot, chemically active fluids. Common products include rocks such as schist, gneiss, marble, and quartzite, which arise from limestone, slate from shale, or granite-derived rocks through complete or partial recrystallization.

The study of endurmyndun helps reconstruct tectonic histories and crustal evolution, and it distinguishes metamorphic rocks from igneous and sedimentary rocks based on mineralogy, texture, and formation conditions.