What is isotropic indicatrix?
The Isotropic Indicatrix The optical indicatrix is simply a three dimensional object constructed by drawing vectors of length proportional to the refractive index for light vibrating parallel to the vector direction from a central point. The ends of all of the vectors are then connected to form the indicatrix.
What minerals are anisotropic?
Anisotropic Minerals. Isotropic minerals have crystal structures which have the same structure in every direction. They belong to the isometric crystal system. All other minerals are anisotropic, meaning their crystal structures vary with direction.
Which minerals are pleochroic?
Pleochroic halos are commonly found in rock-forming minerals—for example, biotites, fluorites, and amphiboles. The most common inclusions are the minerals zircon, xenotime, apatite, and monazite.
What is biaxial indicatrix?
The biaxial indicatrix has three principle axes, labeled α, β, and γ. Directions that have refractive indices between α and β, are referred to as α’. Directions with refractive indices between γ and β are referred to as γ’. Note that the β direction also must occur in the plane that includes α and γ.
Is Gypsum isotropic or anisotropic?
anisotropic elastic
Each single gypsum crystal exhibits an anisotropic elastic behavior, arising from its crystallographic structure.
What is anisotropy material?
Anisotropic materials, also known as “triclinic” materials, are direction-dependent mediums that are made up of unsymmetrical crystalline structures. In other words, the mechanical properties of anisotropic materials depend on the orientation of the material’s body.
Are all anisotropic minerals pleochroic?
Anisotropic minerals are not. If no color variation is observed on rotation under plane-polarized light then the mineral is non-pleochroic. Dichroic minerals are generally always hexagonal, trigonal, or tetragonal. Pleochroic minerals are generally always orthorhombic, monoclinic, or triclinic.
What is uniaxial Indicatrix?
The uniaxial indicatrix is constructed by first orienting a crystal with its c-axis vertical. Since the c-axis is also the optic axis in uniaxial crystals, light traveling along the c-axis will vibrate perpendicular to the c-axis and parallel to the ω refractive index direction.
Is calcite isotropic or anisotropic?
Calcite has an anisotropic crystalline lattice structure that interacts with light in a totally different manner than isotropic crystals. The polymer illustrated in Figure 1(c) is amorphous and devoid of any recognizable periodic crystalline structure.
What is anisotropic soil?
Definition. Anisotropy is the property of being directionally dependent, as opposed to isotropy, which means homogeneity in all directions. It can be defined as a difference in one soil physical property along different directions.
Is tourmaline a pleochroic?
Tourmaline. Tourmaline forms triangular prismatic crystals and can show a range of body colours. It also exhibits intense pleochroism.
Is Clinopyroxene a pleochroic?
Clinopyroxene – XYZ2O. Optical properties: Colour and Pleochroism: Usually colourless, gray, pale green or pale brown, darker colours associated with Fe-rich varieties titanaugite is more distinctly coloured from brown/pink to violet. Cleavage: Parallel to {110}, which intersect at 90°.
Does tourmaline show pleochroism?
Tourmaline forms triangular prismatic crystals and can show a range of body colours. It also exhibits intense pleochroism.
Is quartz isotropic or anisotropic?
Quartz crystals are birefringent, so they exhibit optical anisotropy.
What is soil anisotropy?
Soil Anisotropy: Mechanisms and Hydrologic Consequences. Anisotropy, which is the opposite of “isotropy,” is a term used to denote preferential flow direction in soils and other geologic materials. If soil consisted of perfectly spherical grains, flow rates would be isotropic – the same in all directions, other factors being equal.
What is the indicatrix of a mineral?
The indicatrices are the representation of the values for “n” for all the directions of vibration of a crystal. By thus representing the minerals, three types of geometric shapes appear: -For some minerals, the optic indicatrix is a sphere. This is the case of those that are isotropic.
What is an optic indicatrix?
The geometric figure which results is called the optic indicatrix. The indicatrices are the representation of the values for “n” for all the directions of vibration of a crystal. By thus representing the minerals, three types of geometric shapes appear:
Why are alluvial sediments anisotropic?
Todd (1980) noted that, especially for unconsolidated undisturbed alluvial material, anisotropic behavior is the norm. Two reasons for anisotropy in unconsolidated sediments include: i)individual particles are rarely spherical. When they settle out of the water column, they land with their flat sides down.