Note on the occurrence of niobium-rich zirconolite in carbonatitic rocks of Santiago Island (Cape Verde Republic)

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Authors:Silva, L. Celestino; Figueiredo, M. O.
Author Affiliations:Primary:
LEPPU, Junta Invest. Cient. Ultramar, Portugal
Other:
LTFQMP, Portugal
Volume Title:Garcia de Orta, Serie de Geologia
Source:Garcia de Orta, Serie de Geologia, 4(1-2), p.1-6. Publisher: Junta de Investigacoes Cientificas do Ultramar, Lisbon, Portugal. ISSN: 0378-1240
Publication Date:1980
Note:In English with Portuguese summary. 21 refs.; 7 anal., 2 tables, 1 plate, sketch map
Summary:A brief geological and petrographic description of a new terrestrial occurrence of Nb-rich non-metamict zirconolite is presented. This mineral occurs as an accessory mineral in carbonatites of the Canafistula carbonatitic plug in Santiago Island (Republic of Cape Verde). Crystals are generally euhedral, flattened parallel (001), mean grain size 0.1-0.2 mm. XRD data are listed, strongest reflections at 2.94, 2.52, 1.82 and 1.75 A. The mineral is monoclinic; a 12.33, b 7.27, c 11.44 A, beta 100.5°, calculated density 5 g/cm3 and possible space groups C2/c and Cc, on the basis of single-crystal X-ray study. As far as known, it is the first recording of zirconolite in an oceanic environment. [L.A.B.]
Subjects:Carbonatites; Electron probe data; Igneous rocks; Ions; Mineral composition; Mineral data; Mineralogy; Minerals; Niobates; Oxides; X-ray data; Zirconolite; Africa; Atlantic Ocean Islands; Cape Verde Islands; Santiago Island
Coordinates:N144000 N172000 W0223000 W0253000
Abstract Numbers:83M/0725
Record ID:1983002979
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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