Thin Section Description Of Granite

Petrography is a branch of petrology that focuses on detailed descriptions of rocks someone who studies petrography is called a petrographer the mineral content and the textural relationships within the rock are described in detail.

Thin section description of granite.

Strictly speaking granite is an. The large pink carlsbad twinned k feldspar megacrysts dominate the thin section. This sample is a less evolved portion of the intrusion which was associated with the tourmaline and topaz rich intrusions and mineralisation. Granite ˈ ɡ r æ n ɪ t is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture.

Biotite metaluminous granite showing a close up of one crystal. The second is a thin section rock description where you have a slice of the rock which is on a glass slide making it possible to view the rock under a microscope. This means that biotite in standard thin sections rarely goes completely extinct. To link to this object paste this link in email im or document to embed this object paste this html in website.

Granites can be predominantly white pink or gray in color depending on their mineralogy the word granite comes from the latin granum a grain in reference to the coarse grained structure of such a completely crystalline rock. This sample of biotite rich granite comes from the luxulyan quarry in the luxulyan valley in south east cornwall. The mineralogy of this granite is relatively simple biotite quartz and two feldspars plagioclase and k feldspar. These are photographs of a thin section of granite magnification 10x perhaps the most common igneous rock we encounter.

The thin section illustrates the quartz rich nature of the rock which. By comparing the plane polarized light left and crossed polarizer right images we can see that there are three minerals in this granite. Hand specimen descriptions focus on physical properties of the rocks whereas the thin section descriptions looks at optical properties instead. Quartz thin section photomicrographs are taken in plane polarized light and cross polarized light and can easily be recognized under the microscope.

Damage produced during thin section grinding causes speckles of light in the biotite where the crystal lattice has been deformed.