Thin Section Granites

These are photographs of a thin section of granite magnification 10x perhaps the most common igneous rock we encounter.

Thin section granites.

Biotite metaluminous granite showing a close up of one crystal. Identification tables for common minerals in thin section these tables provide a concise summary of the properties of a range of common minerals. This means that biotite in standard thin sections rarely goes completely extinct. 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.

Enjoy the videos and music you love upload original content and share it all with friends family and the world on youtube. Damage produced during thin section grinding causes speckles of light in the biotite where the crystal lattice has been deformed. Granites in the slate belt together with those in the shan scarps segment of the mogok metamorphic belt to the west fig. Biotite brown grains in plain light and pinkish brown with crossed polars the brown color is due to a property called.

Strictly speaking granite is an. Within the tables minerals are arranged by colour so as to help with identification. The presence of these aluminous silicate minerals are commonly used as a means of initially classifying granites as s type. Photomicrographs of these minerals in thin section from s type granites of the lachlan fold belt are shown in figure 2a and 2b.

S type granites can also contain aluminium rich iron and magnesium rich biotites. Each thin section was first scanned in unpolarized light and then again between two sheets of crossed polaroid film aligned parallel to the thin section edges. These are photomicrographs very thin slices of rock seen in plane polarised light or between crossed polarisers when the colours seen are produced by interference of light. Quartz thin section photomicrographs are taken in plane polarized light and cross polarized light and can easily be recognized under the microscope.

Originally plane polarized scanning in separate e w n s orientations was attempted to highlight pleochroic variation but this ultimately had to be abandoned due to significant. Some common rock types as seen under the microscope. If a mineral commonly has a range of colours it will appear once for each colour. Rocks under the microscope.