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GEOREF RECORD

Tourmaline of the elbaite-dravite series from an elbaite-subtype pegmatite at Blizna, southern Bohemia, Czech Republic

Milan Novak, Julie B. Selway, Petr Cerny, Frank C. Hawthorne and Luisa Ottolini
Tourmaline of the elbaite-dravite series from an elbaite-subtype pegmatite at Blizna, southern Bohemia, Czech Republic
European Journal of Mineralogy (June 1999) 11 (3): 557-568

Abstract

The elbaite-subtype pegmatite at Blizna, near Cerna v Posumavi, S Bohemia, intrudes dolomite-calcite marble. It consists of two distinct units (A and B) and has a narrow exocontact zone along the edge of the pegmatite. The sequence of crystallization in unit A is Ca-rich schorl-elbaite --> Ca-rich elbaite-schorl-dravite --> Mn-rich elbaite --> Mn-rich liddicoatite --> liddicoatite-elbaite, typical of tourmaline from elbaite-subtype pegmatites. In unit B the tourmaline crystallization sequence is Na-rich uvite --> Ca-rich schorl-elbaite-dravite --> Ca-rich Mg-bearing elbaite --> (Ca,Mn)-rich elbaite --> Mn-rich liddicoatite-elbaite --> Na-rich liddicoatite. Tourmaline from the exocontact ranges from Na-rich uvite- --> Ca-rich dravite --> dravite-elbaite --> Ca-rich Mg-bearing elbaite --> liddicoatite-elbaite. Representative EPMA results are tabulated from 23 tourmalines of these three units. The intermediate elbaite-schorl-dravite and elbaite-dravite solid solution series from unit B and from the exocontact zone are a result of interaction between (B,F,Li)-rich pegmatite fluid and (Ca,Mg)-rich fluids from the host marble. The factors controlling formation of elbaite-dravite in rocks may be summarized: high activities of Li, Mg, Al and B and a high Li/Mg ratio in the parent medium, acidic conditions with pH < approximately 6, and lack of holmquistite. Thus, tourmaline of the elbaite-dravite series may be expected in highly contaminated elbaite-subtype pegmatites penetrating marble and in holmquistite-free contact aureoles around complex pegmatites.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 11
Serial Issue: 3
Title: Tourmaline of the elbaite-dravite series from an elbaite-subtype pegmatite at Blizna, southern Bohemia, Czech Republic
Affiliation: Moravian Museum, Department of Mineralogy and Petrography, Brno, Czech Republic
Pages: 557-568
Published: 199906
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 27
Accession Number: 1999-046905
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sects.
N48°31'60" - N51°04'00", E12°05'60" - E16°49'60"
Secondary Affiliation: University of Manitoba, CAN, CanadaCentro di Studio per la Cristallochimica e la Cristallografia, ITA, Italy
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199916
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