Search results
Results From The WOW.Com Content Network
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:
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 ...
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.
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 ...
A shield is a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. [1] These rocks are older than 570 million years and sometimes date back to around 2 to 3.5 billion years.
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".
Formed from or containing a high proportion of calcium carbonate in the form of calcite or aragonite, used of a sediment, sedimentary rock, or soil type. calcite A mineral that is the crystalline form of calcium carbonate (CaCO 3), showing trigonal symmetry and a great variety of mineral habits. It is one of the commonest of minerals in ...