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The mafic minerals in the TTG rock body, possibly biotite, were weathered, which introduced a brownish coating on the TTG rock surface. Tonalite–trondhjemite–granodiorite ( TTG ) rocks are intrusive rocks with typical granitic composition ( quartz and feldspar ) but containing only a small portion of potassium feldspar .
Alkali feldspar granite, some varieties of which are called 'red granite', [1] is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar (K-spar). It is a dense rock with a phaneritic texture. The abundance of K-spar gives the rock a predominant pink to reddish hue; peppered with minor amounts of black minerals. [2] [3]
Experts explain whether ice or heat for back pain will lead to better relief, and the best time to use each. ... a good rule of thumb is to pick either cold or heat and trial for 20 minutes to see ...
Felsic magmas and lavas have lower temperatures of melting and solidification than mafic magmas and lavas. Felsic rocks are usually light in color and have specific gravities less than 3. The most common felsic rock is granite. Common felsic minerals include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars (albite-rich).
Macroscopic aspects of nepheline syenite are similar to those of granite. The presence of nepheline and absence of quartz are the fundamental difference. Biotite is generally of low content and the main mafic minerals are clinopyroxene (±) and amphibole (±). The macroscopic colour is grey, being little darker than granite.
Mafic enclave in granite rock, at Yosemite National Park Granite forms from silica-rich ( felsic ) magmas. Felsic magmas are thought to form by addition of heat or water vapor to rock of the lower crust , rather than by decompression of mantle rock, as is the case with basaltic magmas. [ 20 ]
Magma mixing occurs when magmas of a different composition intrude a larger magma body. In some cases, the melts are immiscible and stay separated to form pillow like collections of denser mafic magmas on the bottom of less dense dense felsic magma chambers. The mafic pillow basalts will demonstrate a felsic matrix, suggesting magma mingling ...
The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older basic rock class. [9] Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava.