Red Granite Thin Section

Fluorapatite ilmenite and titanite are also present in minor amounts.

Red granite thin section. The thin section contains small grains of riebeckite a blue green amphibole and arfvedsonite a blue green amphibole. Within the tables minerals are arranged by colour so as to help with identification. These are photographs of a thin section of granite magnification 10x perhaps the most common igneous rock we encounter. A rock thin section is created by gluing a small piece of rock onto a glass slide then grinding it down to a thickness of 30 microns the average human hair is about 100 microns in diameter so that light shines through it when examined under the microscope.

Damage produced during thin section grinding causes speckles of light in the biotite where the crystal lattice has been deformed. By comparing the plane polarized light left and crossed polarizer right images we can see that there are three minerals in this granite. This means that biotite in standard thin sections rarely goes completely extinct. If a mineral commonly has a range of colours it will appear once for each colour.

Both minerals are abundant and visible in the thin section but the grains are too small to allow the user to recognise the key. 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. In thin section the sample is very fine grained for a rock characterised as a granite.

The large pink carlsbad twinned k feldspar megacrysts dominate the thin section.