metacryst

A metacryst is a crystal that forms within a pre-existing rock during metamorphism. This process, known as neomorphism, involves the recrystallization of minerals under conditions of increased temperature and pressure, leading to the growth of new, often larger, crystals. Metamorphism can occur due to tectonic forces, igneous intrusions, or burial deep within the Earth's crust. The composition of the metacryst depends on the original minerals present in the rock and the specific metamorphic conditions. Common examples of metacrysts include garnet, staurolite, and andalusite, which are often found in metamorphic rocks like schists and gneisses. The formation of metacrysts can significantly alter the texture and appearance of the original rock. The study of metacrysts is crucial for understanding the geological history and metamorphic processes that a rock has undergone. Their size, shape, and orientation can provide valuable clues about the temperature, pressure, and deformation history of the metamorphic event.