What is a Phaneritic texture and how does it form?
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What is a Phaneritic texture and how does it form?
A phaneritic texture is developed by the slow cooling and crystallisation of magma trapped within the Earth’s crust and is characteristic of plutonic rocks.
Is basalt a Hypocrystalline?
Basalts are porphyritic, with calcic plagioclase (An72–92Ab7–27Or0–1), ferroan enstatite (En59–68Fs29–37Wo3–4) and augite (En38–39Fs18–20Wo41–44) phenocrysts, in a hypocrystalline groundmass made up of bytownite (An71–85Ab14–28Or1), augite (En37–38Fs19Wo43–44), ferroan enstatite (En62–68Fs30–35Wo1–4) and rare pigeonite …
What’s the meaning of phaneritic?
[ făn′ə-rĭt′ĭk ] Of or relating to an igneous rock in which the crystals are so coarse that individual minerals can be distinguished with the naked eye. Phaneritic rocks are intrusive rocks that cooled slowly enough to allow significant crystal growth.
What is Trachytic texture?
Trachytic is a texture of extrusive rocks in which the groundmass contains little volcanic glass and consists predominantly of minute tabular crystals, namely, sanidine microlites. The microlites are parallel, forming flow lines along the directions of lava flow and around inclusions.
What is Vitrophyric texture?
This is variety of inequigranular porphyritic texture in which larger crystals known as phenocrysts are embedded in a glassy ground mass.
Is Basalt a Hypocrystalline?
What is the texture of phaneritic rocks?
Coarse-grained textures generally indicate magmas that slowly cooled deep underground.
How are phaneritic rocks formed?
Phaneritic (phaner = visible) textures are typical of intrusive igneous rocks, these rocks crystallized slowly below Earth’s surface. As magma cools slowly the minerals have time to grow and form large crystals.
What is cumulate texture?
Cumulate rocks are named according to their texture; cumulate texture is diagnostic of the conditions of formation of this group of igneous rocks. Cumulates can be deposited on top of other older cumulates of different composition and colour, typically giving the cumulate rock a layered or banded appearance.
What is Amygdaloidal texture?
A related texture is amygdaloidal in which the volcanic rock, usually basalt or andesite, has cavities, or vesicles, that are filled with secondary minerals, such as zeolites, calcite, quartz, or chalcedony. Individual cavity fillings are termed amygdules (American usage) or amygdales (British usage).
