BERYL-TANTALITE PEGMATITES OF NORTHEASTERN BRAZIL

Abstract

Research Article| November 01, 1945 BERYL-TANTALITE PEGMATITES OF NORTHEASTERN BRAZIL W. D JOHNSTON, JR. W. D JOHNSTON, JR. FOREIGN ECONOMIC ADMINISTRATION, c/o AMERICAN EMBASSY, RIO DE JANEIRO, BRAZIL. Search for other works by this author on: GSW Google Scholar Author and Article Information W. D JOHNSTON, JR. FOREIGN ECONOMIC ADMINISTRATION, c/o AMERICAN EMBASSY, RIO DE JANEIRO, BRAZIL. Publisher: Geological Society of America Received: 08 Mar 1945 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1945, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1945) 56 (11): 1015–1070. https://doi.org/10.1130/0016-7606(1945)56[1015:BPONB]2.0.CO;2 Article history Received: 08 Mar 1945 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation W. D JOHNSTON; BERYL-TANTALITE PEGMATITES OF NORTHEASTERN BRAZIL. GSA Bulletin 1945;; 56 (11): 1015–1070. doi: https://doi.org/10.1130/0016-7606(1945)56[1015:BPONB]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Microcline-muscovite-quartz pegmatites in Northeastern Brazil have yielded approximately 600 metric tons of tantalite and 8000 metric tons of beryl, between 1937 and 1944. Other economic minerals are cassiterite, muscovite, amblygonite, and spodumene.The regional rocks are pre-Cambrian schists and quartzites intruded by granites.The pegmatites range from homogeneous textures without notable internal differentiation to heterogeneous textures with pronounced internal zoning. In the latter type, the essential minerals—microcline, muscovite, and quartz—form gigantic crystals, and the accessory minerals—tantalite, beryl, spodumene, and amblygonite—crystallize on a comparable scale.Aside from late albitization of the microcline, there appears to be little evidence that the differentiation in the heterogeneous pegmatites resulted from a series of complex replacements. The field evidence appears, rather, to indicate deposition in a single cycle with a progressive increase in crystal size from walls to center.Forty-two characteristic heterogeneous pegmatites are described, and plane-table sketch maps for some of them are reproduced. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.