The identification of rock slices is a very practical work. For some types of rocks that are not commonly encountered, even after decades of work, they may not be able to be expertly identified. Recently, I encountered a very special rock flake during the identification of rock flakes. It looks like silty mudstone under single polarized light. However, careful observation shows that some clay minerals in the rock have recrystallized to form oriented sericite. Lai rock has undergone slight deterioration. What is puzzling is that dark spots of different sizes, hexagonal or elliptical, can be seen in the orthogonal polarization. The minerals in the spots are very weak, and some spots have a ring-shaped structure and are circular. Nuclear. At first I thought it was garnet, but under single-polarized light, no mineral crystals existed. Obviously it was not garnet. Observe carefully after magnification: in the dark spots, the clay minerals are mainly chlorite; while the matrix part is mainly sericite or fine scaly mica, and the content of chlorite is not high. Except for the slight difference in mineral composition between the spots and the matrix, the other structures are very similar.
