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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.
The amphibolite facies is a facies of medium pressure and average to high temperature. It is named after amphiboles that form under such circumstances. It has the following mineral assemblages: In metabasites: hornblende + plagioclase ± epidote, garnet, cummingtonite, diopside, biotite; In metapelites:
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.
Gore Mountain Garnet, found in the Adirondack Mountains in New York, contains the world's largest garnets. [1] [2] The rock that holds these garnets, garnet amphibolite, is sometimes referred to as 'black ore' or 'dark ore.' [1] [3] This rock formation formed during metamorphism during the Ottawan phase of the Grenvillian orogeny, and extremely high temperatures combined with introduction of ...
They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction, and distortion. Metamorphic rock can be formed locally when rock is heated by the intrusion of hot molten rock called magma from the Earth's interior. The study of metamorphic rocks (now exposed at the Earth's surface following ...
Blastomylonites are coarse grained, often sugary in appearance without distinct tectonic banding.; Ultramylonites usually have undergone extreme grainsize reduction. In structural geology, ultramylonite is a kind of mylonite defined by modal percentage of matrix grains [clarify] more than 90%. [4]
The hunter-gatherers used spears, bows and arrows to catch their prey, Bradtmöller said. A secondary structure may have been used to create the bottleneck, but the research team hasn’t found ...
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.