What is the description of garnet amphibolite?
Petrologist’s definition The garnet amphibolite is a medium size grained (0.1 to 0.2 mm), compact, brownish to greenish grey, somewhat banded, metamorphic rock. The metamorphism has considerably flattened and elongated the mineral grains to produce a banded texture, in between schistose and coarse- grained.
Does amphibolite have garnet?
Amphibolite is a coarse-grained metamorphic rock that is composed mainly of green, brown, or black amphibole minerals and plagioclase feldspar. It can also contain minor amounts of other metamorphic minerals such as biotite, epidote, garnet, wollastonite, andalusite, staurolite, kyanite, and sillimanite.
What does amphibolite look like?
Amphibolite is a grouping of rocks composed mainly of amphibole and plagioclase, with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky) structure. The small flakes of black and white in the rock often give it a salt-and-pepper appearance.
What color is amphibolite?
Amphiboles yield water when heated in a closed tube and fuse with difficulty in a flame. Their colour ranges extensively from colourless to white, green, brown, black, blue, or lavender and is related to composition, principally the iron content.
What type of rock is amphibolite?
Amphibolite, a rock composed largely or dominantly of minerals of the amphibole group. The term has been applied to rocks of either igneous or metamorphic origin. In igneous rocks, the term hornblendite is more common and restrictive; hornblende is the most common amphibole and is typical of such rocks.
What is the most likely Protolith of amphibolite?
Amphibolite is a common metamorphic rock. It is made of amphiboles (usually hornblende) and plagioclase. Most samples have a relatively simple composition: hornblende + plagioclase. Garnet (almandine), pyroxene, biotite, titanite, magnetite, epidote, chlorite, and quartz are also frequent constituents.
What is amphibolite protolith?
What do non-foliated rocks look like?
Non-foliated metamorphic rocks do not have a layered or banded appearance. Examples of nonfoliated rocks include: hornfels, marble, novaculite, quartzite, and skarn. Gneiss is a foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains.
What makes a schist?
Schist is medium grade metamorphic rock, formed by the metamorphosis of mudstone / shale, or some types of igneous rock, to a higher degree than slate, i.e. it has been subjected to higher temperatures and pressures. These larger crystals reflect light so that schist often has a high lustre, i.e. it is shiny.
What’s the Protolith of amphibolite?
Amphibolite is a metamorphosed mafic igneous rock (basalt, gabbro) although it is usually difficult to determine the protolith because original features are often obliterated. Basalt is composed of pyroxene + plagioclase. Schistose rocks with a similar composition are hornblende schists.
What is the geochronology of garnet amphibolite?
Metamorphism and geochronology of garnet amphibolite from the Beishan Orogen, southern Central Asian Orogenic Belt: Constraints from P-T path and zircon U-Pb dating Four periods of metamorphism in the garnet amphibolite define a near-isothermal decompression of a clockwise P-T-t path.
What can amphibolite be used for on Earth?
If enough garnet is present and of proper quality, the amphibolite can be mined and the garnet recovered for use as an abrasive. Rock & Mineral Kits: Get a rock, mineral, or fossil kit to learn more about Earth materials.
What kind of minerals are found in amphibolite rocks?
Amphibolite is a coarse-grained metamorphic rock that is composed mainly of green, brown, or black amphibole minerals and plagioclase feldspar. The amphiboles are usually members of the hornblende group. It can also contain minor amounts of other metamorphic minerals such as biotite, epidote, garnet, wollastonite,…
How old is the Beishan garnet amphibolite?
Moreover, the U-Pb dating of the Beishan garnet amphibolite indicates an age of 301.9 ± 4.7 Ma for the protolith and 281.4 ± 8.5 Ma for the peak metamorphic age.