ENE Exam 2 Practice

A phase change is about rearranging the internal arrangement of atoms in a mineral without changing its chemical composition. When temperature or pressure shifts, a mineral can transform into a different mineral that has the same formula but a different crystal structure—that’s polymorphism. For example, calcite and aragonite are both CaCO3, but their atoms are arranged differently. The same idea applies to other polymorphs like quartz in its different high- and low-temperature forms. Metamorphism is the broader process that can drive mineral changes, but it isn’t defined by keeping the same composition with a new structure. Recrystallization mainly changes grain size or the form of the same mineral, and neocrystallization introduces minerals with new chemicals. So this scenario fits a phase change.