Uranium and thorium are surprisingly not the most common radioactive isotopes in the Earth's crust. Instead, that title goes to a specific isotope of calcium or rubidium depending on what definition you are using. this video discusses the 10 most common naturally occurring isotopes that occur on Earth through the perspective of a geologist. Thumbnail Photo Credit: This work "CarnotiteAZ1", is a derivative of a photo (resized, cropped, text overlay, overlaid with GeologyHub made graphics (the image border & the GeologyHub logo)) from "Carnotite AZ AndersonMine PvdL-9.jpg", by: Henk Smeets, jsjgeology, 2023, Posted on Wikimedia Commons, Wikimedia Photo link: https://commons.wikimedia.org/wiki/File:Carnotite_AZ_AndersonMine_PvdL-9.jpg, Photo link: https://www.tomeikminerals.com/usa-arizona/, Website: https://www.tomeikminerals.com/, CC BY 4.0. "CarnotiteAZ1" is used & licensed under CC BY 4.0 by Youtube.com/GeologyHub 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) Google Earth imagery used in this video: ©Google & Data Providers 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): Public Domain: https://creativecommons.org/publicdomain/mark/1.0/ CC0 1.0: https://creativecommons.org/publicdomain/zero/1.0/legalcode CC BY 3.0: https://creativecommons.org/licenses/by/3.0/legalcode CC BY SA-3.0: https://creativecommons.org/licenses/by-sa/3.0/legalcode CC BY 4.0: https://creativecommons.org/licenses/by/4.0/legalcode CC BY SA-4.0: https://creativecommons.org/licenses/by-sa/4.0/legalcode Sources/Citations: [1] U.S. Geological Survey [2] Wikimedia Commons (links specified in video graphics), CC BY-SA 4.0 [3] https://images-of-elements.com/, by: https://images-of-elements.com/, Photo link: https://images-of-elements.com/rubidium.jpg, Rubidium Element Page: https://images-of-elements.com/rubidium.php, CC BY 3.0 0:00 Radioactive Isotopes 1:09 Calcium-48 2:38 Rubidium 3:14 Uranium & Thorium 3:59 Potassium 4:49 REEs & Rhenium