Which mineral is commonly present in amphibolite facies?

Amphibole, diopside, epidote, plagioclase, almandine and grossular garnet, and wollastonite are minerals typically found in rocks of the amphibolite facies. The disappearance of epidote and increase in calcium in plagioclase are characteristic chemical changes as metamorphic intensity increases through this facies.

What does amphibole contain?

Amphibole defines an important group of dark-colored rock-forming inosilicate minerals composed of double chain SiO4 tetrahedra linked at the vertices and generally containing ions of iron and/ or magnesium in their structures.

What rock does amphibolite turn into?

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.

Is amphibolite felsic or mafic?

The name amphibolite has been used in geological literature for nearly 200 years, since Brongniart (1813).

How is amphibolite rock formed?

How Does Amphibolite Form? Amphibolite is a rock of convergent plate boundaries where heat and pressure cause regional metamorphism. It can be produced through the metamorphism of mafic igneous rocks such as basalt and gabbro, or from the metamorphism of clay-rich sedimentary rocks such as marl or graywacke.

What are the description of the amphibolite?

Amphibolite (/æmˈfɪbəlaɪt/) is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky) structure.

How do you identify amphibolite?

Long prismatic, acicular, or fibrous crystal habit, Mohs hardness between 5 and 6, and two directions of cleavage intersecting at approximately 56° and 124° generally suffice to identify amphiboles in hand specimens. The specific gravity values of amphiboles range from about 2.9 to 3.6.

What are the properties of amphibole?

Typically, amphiboles form as long prismatic crystals, radiating sprays and fibrous aggregates. They are generally dark coloured though their colours can range from colourless to white, green, brown, black, blue or lavender. This property is related to composition, particularly iron content.

What is the mineral composition of amphibolites?

The mineral composition of the amphibolites is simple and mostly contains hornblende and plagioclase, with variable amounts of anthophyllite, garnet, mica, quartz, and epidote. The rocks may originate from pelitic sediments, with amphibole (hornblende), plagioclase, and typically include green pyroxene.

Is amphibolite an igneous rock?

This specimen is actually an igneous rock. Some geologists call an igneous rock composed primarily of amphibole minerals an amphibolite or “hornblendite.” USGS image. Amphibolite has a variety of uses in the construction industry.

What metamorphic rocks are associated with amphibolites?

Amphibolites are often associated with other metamorphic rocks like quartzite, schist, marble, gneiss. These rocks represent different protoliths that were metamorphosed during the same mountain building episode. Stripes of metamorphic rocks like these are often next to one another in geological maps.

What is the texture of amphibolite?

The metamorphism sometimes flattens and elongates the mineral grains to produce a schistose texture. Amphibolite: Some amphibolites are greenish, as determined by the color of the amphibole minerals. This specimen is actually an igneous rock.