Mineral optic property
Minerals are naturally occurring solid compounds, which have a wide range of optical properties. The most common optical properties of minerals are birefringence, pleochroism, and anisotropy. The optical properties of minerals are dependent on their composition, composition alteration and crystalline structure. The three optical properties enhance the analysis of various minerals and are an invaluable tool for geologists.
Birefringence is the property of a mineral to split a single beam of light into two beams of unequal velocity. This optical property is created in materials that have a double refractive index. Low grade birefringence minerals are difficult to distinguish under light microscopy because they have very scant differences in their refractive indices and dispersion. Examples of minerals with low birefringence are quartz, muscovite and orthoclase.
Pleochroism is a property of a mineral to show different colors under different direction of incidence or orientation of a light. It is seen in minerals with a single refractive index. The colors shown in pleochroic minerals are caused by the absorption of certain colors of the spectrum. Examples of pleochroic minerals are tourmaline, green hornblende, and andalusite.
Anisotropy is the property of certain minerals to show different colors due to interference in light rays traveling in different directions. It is expressed when visible light is composed of a range of different wavelength. In anisotropic minerals, the refractive index and birefringence are different along different optical axes. Examples of anisotropic minerals are biotite, corundum and cordierite.
Optical properties of minerals are important in their identification, especially in the field of geology. They provide an opportunity to understand and observe the compositions, structures and properties of different minerals. Birefringence, pleochroism and anisotropy provide a wide range of optical tools to identify different types of minerals. These properties are essential in the study of mineralogy and make it possible to understand the significant chemical compositions and formation of minerals.
In conclusion, understanding the optical properties of minerals is an essential part of the study of geology, mineralogy and crystallography. The three optical properties of birefringence, pleochroism, and anisotropy enhance the analysis of different minerals and allow geologists to identify them. They provide a valuable tool to understand the compositions, structure, and properties of minerals. These properties are essential for geologists to understand the significant chemical compositions and formation of minerals.
