Final answer:
Foliated metamorphic rocks have a layered texture due to aligned mineral crystals, while non-foliated metamorphic rocks lack this layering. Metamorphic rocks form from the alteration of pre-existing rocks under high temperature or pressure.
Step-by-step explanation:
Foliated metamorphic rocks are a type of metamorphic rock that have a layered texture. In these rocks, the mineral crystals are aligned with each other, resulting in parallel planes along which the rock splits or overlapping sheets of platy minerals. Examples of foliated metamorphic rocks include slate, gneiss, and phyllite.
Non-foliated metamorphic rocks, on the other hand, do not have a layered texture. The mineral crystals in these rocks have grown in many directions and do not show alignment. Examples of non-foliated metamorphic rocks include marble and quartzite.
Metamorphic rocks are formed when pre-existing rocks, either igneous or sedimentary, undergo physical or chemical alteration due to high temperature or pressure. This alteration can result in the development of patterns or orientations in the minerals, known as foliation.