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Metamorphic rock naming can be based on protolith, mineral composition, texture, or metamorphic facies. Naming based on texture and a pelite (e.g., shale, mudrock) protolith can be used to define slate and phyllite. Texture-based names are schist and gneiss. These textures, from slate to gneiss, define a continually-increasing extent of ...
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 ...
It is generally glassy or fine-grained in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent of granite.
The intergrown phases may be planar or rodlike, depending on the volume proportions of the phases, their interfacial free energies, the rate of reaction, the Gibbs free energy change, and the degree of recrystallization. Lamellar symplectites are common in retrogressed eclogite. Kelyphite is a symplectite formed from the decomposition of garnet ...
This is a list of minerals which have Wikipedia articles. Minerals are distinguished by various chemical and physical properties.
This texture reflects a high content of platy minerals, such as mica, talc, chlorite, or graphite. These are often interleaved with more granular minerals, such as feldspar or quartz . Schist typically forms during regional metamorphism accompanying the process of mountain building ( orogeny ) and usually reflects a medium grade of metamorphism.
[1] [2] Examples are dolomite, which is an aggregate of crystals of the mineral dolomite, [3] and rock gypsum, an aggregate of crystals of the mineral gypsum. [4] Lapis lazuli is a type of rock composed of an aggregate of crystals of many minerals including lazurite , pyrite , phlogopite , calcite , potassium feldspar , wollastonite and some ...