Thin Section Description Of Granite

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

Thin section description of granite.

The classification of rocks is based on the information acquired during the petrographic analysis petrographic descriptions start with the field notes at the. The mineralogy of this granite is relatively simple biotite quartz and two feldspars plagioclase and k feldspar. 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. Biotite brown grains in plain light and pinkish brown with crossed polars the brown color is due to a property called.

Granite ˈ ɡ r æ n ɪ t is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Strictly speaking granite is an. Hand specimen descriptions focus on physical properties of the rocks whereas the thin section descriptions looks at optical properties instead. 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.

This means that biotite in standard thin sections rarely goes completely extinct. This sample is a less evolved portion of the intrusion which was associated with the tourmaline and topaz rich intrusions and mineralisation. Biotite metaluminous granite showing a close up of one crystal. By comparing the plane polarized light left and crossed polarizer right images we can see that there are three minerals in this granite.

The large pink carlsbad twinned k feldspar megacrysts dominate the thin section. Quartz thin section photomicrographs are taken in plane polarized light and cross polarized light and can easily be recognized under the microscope. 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.

Fluorapatite ilmenite and titanite are also present in minor amounts.