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2. Foliation (geology) - Wikipedia

   en.wikipedia.org/wiki/Foliation_(geology)

   Gneiss, a foliated metamorphic rock. Quartzite, a non-foliated metamorphic rock. Foliation in geology refers to repetitive layering in metamorphic rocks. [1] Each layer can be as thin as a sheet of paper, or over a meter in thickness. [1] The word comes from the Latin folium, meaning "leaf", and refers to the sheet-like planar structure. [1]

3. Metamorphism - Wikipedia

   en.wikipedia.org/wiki/Metamorphism

   This causes crystals of platy minerals, such as mica and chlorite, to become rotated such that their short axes are parallel to the direction of shortening. This results in a banded, or foliated, rock, with the bands showing the colors of the minerals that formed them. Foliated rock often develops planes of cleavage.

4. Cleavage (geology) - Wikipedia

   en.wikipedia.org/wiki/Cleavage_(geology)

   The degree of deformation and metamorphism along with rock type determines the kind of cleavage feature that develops. Generally, these structures are formed in fine grained rocks composed of minerals affected by pressure solution. [1] Cleavage is a type of rock foliation, a fabric element that describes the way planar features develop in a ...

5. Texture (geology) - Wikipedia

   en.wikipedia.org/wiki/Texture_(geology)

   In geology, texture or rock microstructure [1] refers to the relationship between the materials of which a rock is composed. [2] The broadest textural classes are crystalline (in which the components are intergrown and interlocking crystals), fragmental (in which there is an accumulation of fragments by some physical process), aphanitic (in which crystals are not visible to the unaided eye ...

6. Metamorphic zone - Wikipedia

   en.wikipedia.org/wiki/Metamorphic_zone

   Often they are named for the most characteristic index mineral of the zone. Whether a certain index mineral occurs is also dependent on the composition of the rock itself. Many index minerals have complicated chemical compositions. If not all necessary elements are abundant, the mineral will not grow. When mapping the metamorphic grade of a ...

7. Rock (geology) - Wikipedia

   en.wikipedia.org/wiki/Rock_(geology)

   The proportion of silica in rocks and minerals is a major factor in determining their names and properties. [7] Rock outcrop along a mountain creek near Orosí, Costa Rica. Rocks are classified according to characteristics such as mineral and chemical composition, permeability, texture of the constituent particles, and particle size.

8. List of rock types - Wikipedia

   en.wikipedia.org/wiki/List_of_rock_types

   The following is a list of rock types recognized by geologists.There is no agreed number of specific types of rock. Any unique combination of chemical composition, mineralogy, grain size, texture, or other distinguishing characteristics can describe a rock type.

9. Porphyroblast - Wikipedia

   en.wikipedia.org/wiki/Porphyroblast

   The most common porphyroblasts in metapelites (metamorphosed mudstones and siltstones) are garnets and staurolites, which stand out in well-foliated metapelites (such as schists) against the platy mica matrix. A similar type of crystal is a phenocryst, a large crystal in an igneous rock.