This Crystal Doubles Images; How This Works

This crystal doubles images, meaning that if you look through it that anything on the other side whether that be text, a person, or a photo of a volcano will appear to be doubled. But, why does this unusual optical property occur when utilizing a crystal of calcite? The answer is a fascinating phenomenon known as birefringence, which this video will explain through the expertise and analysis of a geologist.

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Sources/Citations:
[1] Mindat, https://www.mindat.org/
Note. All mineral data, including birefringence and crystal structures, and the number of isometric minerals were cited from Mindat.org
[2] Mindat, "Pharmacosiderite", https://www.mindat.org/min-3185.html
[3] Mindat, "Rutile", https://www.mindat.org/min-3486.html
[4] Mindat, "Geikielite", https://www.mindat.org/min-1670.html
[5] Mindat, "Cinnabar", https://www.mindat.org/min-1052.html
[6] Mindat, "Carpathite", https://www.mindat.org/min-2162.html
[7] Mindat, "Wattersite", https://www.mindat.org/min-4248.html
[8] Mindat, "Calcite", https://www.mindat.org/min-3185.html
[9] Mindat, "Zircon", https://www.mindat.org/min-4421.html
[10] Mills, S. & Kampf, Anthony & Williams, P. & Leverett, Peter & Poirier, Glenn & Raudsepp, M. & Francis, C.. (2010). Hydroniumpharmacosiderite, a new member of the pharmacosiderite supergroup from Cornwall, UK: Structure and description. Mineralogical Magazine. 74. 10.1180/minmag.2010.074.5.863.

0:00 A Cool Phenomenon
0:29 Light Waves
0:42 Birefringence
2:38 High Birefringence
3:19 Pharmacosiderite
3:43 Other Optical Properties

Видео This Crystal Doubles Images; How This Works канала GeologyHub