Final answer:
During metamorphism, a rock can undergo changes in mineralogy, texture, and chemical composition. This is a result of the rock adapting to new environmental conditions involving heat, pressure, and sometimes chemically reactive fluids.
Step-by-step explanation:
A rock can change during metamorphism in a few different ways. This process can alter the original rock, known as the protolith, through a complex combination of heat, pressure, and chemically reactive fluids. The resulting changes can include a modification to the mineralogy, texture, and chemical composition of the rock.
Texture adaptations can include the development of foliation, which is the alignment of mineral grains in a rock due to directed pressure, resulting in a banded or layered appearance. The minerals can also recrystallize due to heat, forming larger crystals and potentially producing new minerals that were not present in the protolith. Foliated textures are common in metamorphic rocks where pressure dominates, whereas non-foliated textures are seen when mineral changes occur without a preferred alignment.
The chemical composition of a rock can also change if fluids are involved, as they can introduce new elements or remove existing ones, causing the growth of new minerals that are stable under the new metamorphic conditions. Ultimately, the changes occur as the rock adjusts to get stable under its new environmental conditions, which may vary significantly from those of the original formation