Metamorphic reaction

A metamorphic reaction is a chemical reaction that changes a rock’s minerals as pressure, temperature, or fluid composition changes. It may involve solid-state rearrangement, fluid-mediated transport, or both.

Chemical equilibrium: A state in which forward and reverse reactions occur at equal rates, leaving no net change in composition. Mineral stability depends on which assemblage is favored at the rock’s pressure, temperature, and composition.
Metamorphism: The solid-state mineralogical and textural change of rocks under conditions different from those of their formation. Metamorphic reactions are the chemical changes that produce many metamorphic mineral assemblages.
Metamorphic facies: Groups of mineral assemblages characteristic of particular pressure-temperature ranges. Facies summarize the mineral products favored by metamorphic reactions under broad conditions.
Albite breakdown reaction: The reaction in which albite breaks down into jadeite and quartz at elevated pressure. This pressure-sensitive reaction illustrates how changing conditions replace one mineral assemblage with another.
Metastability: Persistence of a state that is not the most stable one because transformation is kinetically hindered. Metastable minerals can survive beyond the conditions where equilibrium predicts their replacement.
Metamorphic reaction kinetics: The study of how quickly mineral-changing reactions proceed under metamorphic conditions. Equilibrium predicts possible products, but kinetics determines whether reactions keep pace with changing conditions.
Pressure-temperature path: The sequence of pressures and temperatures experienced by a rock through time. A rock’s changing path determines which reactions become possible and when.
Metamorphic petrology: The study of metamorphic rocks, their minerals, and the conditions that formed them. Petrologists use reaction products to infer the conditions and processes recorded by rocks.
Andalusite-sillimanite transition: The transformation between andalusite and sillimanite, two polymorphs of Al₂SiO₅. The transition demonstrates how pressure and temperature select among minerals of identical composition.
Metamorphic disequilibrium: A condition in which minerals in a metamorphic rock have not reached mutual chemical equilibrium. Disequilibrium makes it difficult to infer conditions from mineral assemblages alone.

Linked from 14 pages