thorianite Thorianite, from Galle, Sri Lanka. (more) thorianite mineral Ask the Chatbot a Question More Actions Print Cite verifiedCite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style MLA APA Chicago Manual of Style Copy Citation Share Share Share to social media Facebook X URL https://www.britannica.com/science/thorianite Feedback External Websites Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). Feedback Type Select a type (Required) Factual Correction Spelling/Grammar Correction Link Correction Additional Information Other Your Feedback Submit Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article.

　　External Websites Mindat.org - Thorianite Ask the Chatbot a Question Written by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... The Editors of Encyclopaedia Britannica Article History Table of Contents Table of Contents Ask the Chatbot Related Topics: rutile group (Show more) See all related content thorianite, thorium dioxide mineral (ThO2) that is very heavy, hard, and coloured dark gray to brownish black or bluish black. Originally found as waterworn grains and crystals in the gem gravels of Ceylon (now Sri Lanka), thorianite also occurs sparsely in the black river and beach sands of Alaska, Madagascar, and Siberia. The refractory nature and scarcity of thorianite have restricted its commercial use as a source of thorium. It forms a solid-solution series with uraninite in which uranium atoms replace thorium atoms in the crystal structure. Rare earths and radiogenic lead and helium are often present. Varieties containing much uranium have been found in pegmatites in Quebec and Ontario and in serpentine at Easton, Pa. For detailed physical properties, see oxide mineral (table).

　　This article was most recently revised and updated by Amy Tikkanen.