Birefringence

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  1. The numerical difference between the refractive indices of a mineral. This difference results in a display of interference colors when thin sections or small fragments of anisotropic minerals are viewed between crossed polars. Isometric minerals and amorphous materials are isotropic and have the same refractive index in every direction; they have no birefringence and show no interference colors. See also: colors
  2. The property of anisotropic crystals to split a beam of light into two polarized rays that traverse the crystal at different velocities as they pass through it and produce characteristic optical effects that are recognizable with the proper instruments or, in some cases (e.g., calcite), by the eye alone. Syn: double refraction CF: transmitted light

Source: Dictionary of Mining, Mineral, and Related Terms


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