What igneous rock has plagioclase feldspar biotite and amphibole?
Syenite: a plutonic rock composed mainly of alkali feldspar, with subordinate sodic plagioclase, biotite, pyroxene, and amphibole.
What rock contains plagioclase feldspar?
Members of the plagioclase group are the most common rock-forming minerals. They are important to dominant minerals in most igneous rocks of the Earth’s crust. They are major constituents in a wide range of intrusive and extrusive igneous rocks including granite, diorite, gabbro, rhyolite, andesite, and basalt.
What rock is composed of 58 plagioclase feldspar 26 amphibole and 16 biotite?
diorite
A) diorite The rock is composed of 58% plagioclase feldspar, 26% amphibole, and 16% biotite.
Is plagioclase feldspar Intermediate?
Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite). Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende).
What would a rock that contains 30% quartz 20% alkali feldspar and 50% plagioclase feldspar be called?
granite
According to the diagram, granite is defined as a coarse-grained igneous rock containing quartz, feldspar (both alkali and plagioclase feldspar), mica and sometimes amphibole.
Which igneous rock above has the most olivine and amphibole in it?
Peridotite
Peridotite is a coarse-grained intrusive igneous rock that is composed almost entirely of olivine. It may contain small amounts of amphibole, feldspar, quartz, or pyroxene. The specimen shown above is about two inches (five centimeters) across.
What type of rock is plagioclase?
igneous rocks
Plagioclase is found in almost all igneous rocks and most metamorphic rocks, but is less common in sedimentary rocks where it usually weathers to clay minerals or a fine grained variant of muscovite (sericite).
Which igneous rock is dark colored formed by rapid cooling and is composed of plagioclase feldspar olivine and pyroxene?
Basalt
Said crystals are composed of mafic minerals, which are relatively low in silica content and give the rock an overall dark colour. These minerals are commonly pyroxene, olivine and plagioclase feldspar. Basalt is an important rock because it’s produced at mid-ocean ridges, where new oceanic crust is made.
Which rock is formed by recrystallization of unmelted rock material under conditions of high temperature and pressure?
Metamorphic rocks
Metamorphic rocks form as a result of recrystallization of unmelted material under conditions of high temperature and pressure over long periods of time.
How can you tell the difference between plagioclase and alkali feldspar?
Alkali feldspars can often be distinguished from plagioclase feldspars because most grains of the latter exhibit albite twinning (see above Crystal structure), which is manifested by parallel lines on certain cleavage surfaces, whereas grains of alkali feldspars do not.
Which type of igneous rock would you expect to contain 70% plagioclase feldspar?
Igneous Rock Charts
| Texture V | Color> | Medium to Dark Colored: Purple, Greenish |
|---|---|---|
| — | Minerals > | 55-70% plagioclase feldspar 15-40% biotite & amphibole |
| Composition | — | Intermediate |
| Fine = aphanitic | Extrusive volcanic | Andesite |
| Coarse = phaneritic | Intrusive plutonic | Diorite |
How much plagioclase does a mafic rock have?
Intermediate rocks can have up to 25% quartz and 50% to 75% plagioclase. Mafic rocks only have plagioclase (up to 50%), and that plagioclase will be calcium-rich, or anorthitic. The dashed blue lines (labelled a, b, c, d) in Figure 3.4.2 represent four igneous rocks.
What kind of minerals are found in felsic rocks?
Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende). Within these four groups, rocks are named depending on whether they display coarse-grained or fine-grained textures.
What kind of color is plagioclase in granite?
Plagioclase: Usually gray or white in granite, dark-bluish color in gabbro. Striations common. 2 cleavage directions at right angle may be detected.
Which is an example of a porphyritic igneous rock?
Phenocrysts are the crystals surrounded by the matrix; these are usually large, straight-sided, and glassy minerals unless they have been weathered. Porphyritic is used as an adjective to modify the name of any fine-grained igneous rock that has less than 50% phenocrysts in it. Example: Porphyritic basalt, porphyritic andesite.