If you turn this mineral specimen, it quickly changes to a different color. But why? The answer relates to a fascinating property of mineralogy known as pleochroism. Pleochroism can cause certain mineral specimens to appear as two or even three different colors and the range in-between under the same light source. This video is explained by a geologist. Thumbnail Photo Credit: Garden State Minerals, Used with Permission A special thanks to SRC Gems & Garden State Minerals for granting me permission to use video clips & images of their specimens! Also, a special thanks to user toastoftime, who I directly quoted from (with permission) from 1m35s to 1m45s in today's video. Your help was appreciated! If you would like to support this channel, consider using one of the following links: (Patreon: http://patreon.com/geologyhub) (YouTube membership: https://www.youtube.com/channel/UCYeGh5VML5XPr5jYnzh3J6g/join) (Gemstone & Mineral Etsy store: http://prospectingarizona.etsy.com) (GeologyHub Merch Etsy store: http://geologyhub.etsy.com) This video is protected under "fair use". If you see an image and/or video which is your own in this video, and/or think my discussion of a scientific paper (and/or discussion/mentioning of the data/information within a scientific paper) does not fall under the fair use doctrine, and wish for it to be censored or removed, contact me by email at [email protected] and I will make the necessary changes. Various licenses used in sections of this video (not the entire video, this video as a whole does not completely fall under one of these licenses) and/or in this video's thumbnail image (and this list does not include every license used in this video and/or thumbnail image): CC BY-SA 3.0 license: https://creativecommons.org/licenses/by-sa/3.0/legalcode Sources/Citations: [1] Mindat, https://www.mindat.org/ Note. All mineral data, including chemical formula and mineral optical data (isotropic, uniaxial, or biaxial) were cited from Mindat.org [2] Mindat, "Zoisite", https://www.mindat.org/min-4430.html [3] Mindat, "Iolite", https://www.mindat.org/min-5119.html [4] Mindat, "Elbaite", https://www.mindat.org/min-1364.html [5] International Mineralogical Association 0:00 Pleochroism 1:35 Pleochroism Criteria 1:52 Crystal Systems 2:09 Pleochroism Explained 3:32 Dichroic & Trichroic 4:03 Other Optical Phenomenon