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Amphibolite from Cape Cod, Massachusetts Garnet bearing amphibolite from Val di Fleres, Italy. Amphibolite (/ æ m ˈ f ɪ b ə l aɪ t /) is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz.
These show the most well-developed schistosity, defined as the extent to which platy minerals are present and are aligned in a single direction, so that the rock easily splits into plates less than a centimeter (0.4 inches) thick. [24] Gneisses, which are more coarse grained and show thicker foliation than schists, with layers over 5mm thick. [23]
Blueschist on Île de Groix, France Photomicrograph of a thin section of blueschist facies metamorphosed basalt, from Sivrihisar, Turkey. Blueschist (/ ˈ b l uː ʃ ɪ s t /), also called glaucophane schist, is a metavolcanic rock [1] that forms by the metamorphism of basalt and rocks with similar composition at high pressures and low temperatures (200–500 °C (392–932 °F ...
The facies are named after the metamorphic rock formed under those facies conditions from basalt. [79] The particular mineral assemblage is somewhat dependent on the composition of that protolith, so that (for example) the amphibolite facies of a marble will not be identical with the amphibolite facies of a pellite.
The pressures exceed those of greenschist, blueschist, amphibolite or granulite facies. Eclogites containing lawsonite (a hydrous calcium-aluminium silicate) are rarely exposed at Earth's surface, although they are predicted from experiments and thermal models to form during normal subduction of oceanic crust at depths between about 45–300 km ...
Amphibole ()Amphibole (/ ˈ æ m f ə b oʊ l / AM-fə-bohl) is a group of inosilicate minerals, forming prism or needlelike crystals, [1] composed of double chain SiO 4 tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures.
Banded iron formations, sedimentary rock that formed in sea water; Garnet in "faux-amphibolite", Nuvvuagittuq Greenstone Belt. The cummingtonite amphibolite that dominates the belt is unusual that sections of the rock have a grayish-beige color, compared to the dark green of common amphibolites, giving it the nickname "faux-amphibolite".
A form of chlorite schist was popular in prehistoric Native American communities for the production of axes and celts, as well as ornamental items. In the Middle Woodland period , greenschist was one of the many trade items that were part of the Hopewell culture exchange network, sometimes transported over thousands of kilometers.