The optical properties of minerals

Abstract

Certain light-dependent characters of minerals have already been considered. This chapter deals with the optical properties of those minerals which make up the common rocks of the Earth’s crust, the so-called rock-forming minerals. A study of these rock-forming minerals entails their examination under the microscope, either as tiny grains or as thin (~0.03 mm) slices of rocks or minerals suitable for examination in transmitted light. In certain microscope studies, particularly of ores and opaque minerals, the thin slice of rock or ore is polished and examined in reflected light. The descriptions of microscopes and thin-section preparation are deferred until after the principles of optics that underlie the study have been considered.