What is conoscopic?

Conoscopy refers to the study of optical properties of crystals using a polarizing microscope in which the crystal is placed between crossed nicol polarizers and observed under the microscope with a conoscope. This technique provides information on the optical properties of the mineral including its birefringence, optical axis angle, pleochroism, and optical symmetry. It is commonly used in mineralogy, crystallography, geology, and materials science for the identification and characterization of minerals and crystals. Conoscopic observations are useful in the determination of crystallographic symmetry, crystal class, and crystal structures. It is also used in materials science for characterizing the structure and properties of synthetic materials, such as liquid crystals.