During recrystallization, how do grains change?

• A. Identity of minerals changes
• B. Shape and size change without changing mineral identity
• C. They melt
• D. They disappear

Answer: (B)

During recrystallization, minerals rearrange their crystal structure under heat or pressure so that new grains form with the same chemical composition as the original mineral but with different orientations. This relieves internal strain and often leads to grains that are larger and have smoother, more regular shapes. The mineral identity stays the same because no melting or chemical change occurs; it’s a rearrangement of the existing material into bigger or differently oriented grains. Melting would create a liquid phase, and disappearing grains would imply loss, neither of which happens in recrystallization.