Skip to main content


birefringence (double refraction) In optical mineralogy, the ability of anisotropic minerals to split plane-polarized light into two rays as it passes through them. The rays vibrate at right angles to each other and travel along different path lengths within the mineral, depending on the degree of birefringence encountered. As a result, when the two sets of rays emerge from the mineral one set has travelled farther than the other and is retarded. The retardation shows itself as a range of interference colours when the analyser is inserted, and may be determined by reference to an interference colour chart. See MICHEL-LÉVY CHART.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"birefringence." A Dictionary of Earth Sciences. . 25 Mar. 2019 <>.

"birefringence." A Dictionary of Earth Sciences. . (March 25, 2019).

"birefringence." A Dictionary of Earth Sciences. . Retrieved March 25, 2019 from

Learn more about citation styles

Citation styles gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, cannot guarantee each citation it generates. Therefore, it’s best to use citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.