ERS201H5 Lecture Notes - Lecture 13: Riebeckite, Pyroxene, Michael Dirr
Document Summary
Continue in chapter 13 of klein and dutrow. Thin section examination is particularly useful, because minerals have optical properties that can be seen only with high magnification and in certain light conditions. Thin sections are 30 um thick (0. 30 mm) slices of rock, mounted glass (usually 1x2 inches, 2. 5x5 cm) Many minerals that appear opaque in hand-sample, are transparent in thin- section. To prepare thin sections, rock samples are cut into manageable-sized slabs: the slabs are cut into blocks about 1. 5 x 4 cm x 1 cm thick. The 50 microns thick slide is then abraded and polished by hand or on a machine to 30 microns, which may require periodic checking with a microscope. A geometric figure showing the refractive index and vibration direction of light passing through a mineral in any direction. Light moves in all directions through an isotropic substance with equal velocity and vibrates in all directions at right angles to the directions of propagation.
