Which term describes the growth of new minerals that were not present in the original protolith?

• A. Metamorphism
• B. Phase Change
• C. Recrystallization
• D. Neocrystallization

Answer: (D)

Neocrystallization is the idea that new mineral species can form during metamorphism that were not present in the original rock. Under changing temperature, pressure, and often with fluids present, ions dissolved from existing minerals can migrate and re-precipitate as different mineral phases. This is why new minerals appear in the rock even though the original protolith didn’t contain them.

In contrast, recrystallization involves growth or realignment of existing minerals—their shapes and sizes change, but the mineral identities (and overall chemistry) stay the same. A phase change refers to a mineral transforming into another form with the same chemical composition (a polymorph), not creating a completely new mineral species. Metamorphism describes the broader process, which can include neocrystallization, but the specific growth of new minerals is neocrystallization.