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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:
This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic ...
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 ...
[4] [5] [6] A semipelite is defined in part as having similar chemical composition but being of a crystalloblastic nature. [7] Pettijohn (1975) [8] gives the following descriptive terms based on grain size, avoiding the use of terms such as clay or argillaceous which carry an implication of chemical composition. The Ancient Greek terms are more ...
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 ...
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 ...