In Earth Science, particularly in the study of geology and metamorphic rocks, "non-foliated" refers to a type of metamorphic rock that does not exhibit a layered or banded appearance. Unlike foliated metamorphic rocks, which have a distinct alignment of mineral grains due to the directional pressure during metamorphism, non-foliated rocks typically have a more uniform texture and are made up of interlocking crystals that are not aligned.
Common examples of non-foliated metamorphic rocks include:
- Marble: Formed from the metamorphism of limestone, marble is composed primarily of calcite or dolomite and is known for its crystalline texture.
- Quartzite: Formed from the metamorphism of sandstone, quartzite is primarily composed of quartz grains and is known for its hardness and resistance to weathering.
Non-foliated metamorphic rocks can form under conditions of uniform pressure and temperature or can be the result of contact metamorphism, where heat from an intrusion affects the surrounding rock without significant pressure.