Diverse mineral assemblages of primary Be minerals from pegmatites of the Třebíč Pluton, Moldanubian Zone, Czech Republic; an effect of early tourmaline crystallisation

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F25%3A10169880" target="_blank" >RIV/00025798:_____/25:10169880 - isvavai.cz</a>

Alternative codes found

RIV/00216224:14310/25:00143385

Result on the web

<a href="https://doi.org/10.1180/mgm.2025.10148" target="_blank" >https://doi.org/10.1180/mgm.2025.10148</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1180/mgm.2025.10148" target="_blank" >10.1180/mgm.2025.10148</a>

Result language

angličtina

Original language name

Diverse mineral assemblages of primary Be minerals from pegmatites of the Třebíč Pluton, Moldanubian Zone, Czech Republic; an effect of early tourmaline crystallisation

Original language description

Crystallisation of the earliest minerals typically affects the composition of minerals subsequently formed, being controlled by their abundance and the compatibility/incompatibility of the relevant elements. Here we have investigated the effects of early tourmaline crystallisation on the formation of primary Be minerals (beryl and helvine-danalite) in metaluminous intragranitic NYF pegmatites of the T &amp; rcaron;eb &amp; iacute;&amp; ccaron; Pluton, Czech Republic. Tourmaline occurs in different textural-paragenetic types: (a) coarse- to medium-grained aggregates; (b) graphic (Tur+Qz) intergrowths; (c) fine-grained nodules (Tur+Qz+Pl+Kfs); (d) tourmaline pseudomorphs after biotite; (e) interstitial tourmaline; and (f) replacing helvine-danalite. The compositions of primary tourmalines (a), (b) and (c) vary from Ca- and Ti-rich Fe-dravite to Mg-poor schorl and dutrowite, and to magnesio-dutrowite, showing low to moderate Al (5.1-6.1 apfu), variable Mg (0.1-1.9 apfu) and Fe (1.3-2.2 apfu), low Mn (&lt;= 0.1 apfu), low to moderate Ca (0.1-0.4 apfu), and high Ti (&lt;= 0.55 apfu). Type (f) secondary tourmaline is poor in Mg, Ca and Ti (all &lt;= 0.07 apfu), but rich in Na (0.64-0.81 apfu), Fe (0.68-2.17 apfu), Mn (0.31-0.80 apfu), Al (6.57-7.61 apfu), and F (0.37-0.58 apfu). Two distinct assemblages of early-formed Be minerals were recognised: the assemblage beryl +/- phenakite occurs in pegmatites with rare interstitial tourmaline (e), whereas the assemblage helvine-danalite +/- phenakite is characteristic of pegmatites with abundant early tourmaline (a). The assemblages of primary Be minerals in the individual pegmatites reflect how crystallisation and abundance of early tourmaline control the origin and composition of successive primary Be minerals. The crystallisation of abundant early-formed tourmaline depletes the residual melt of elements that are incorporated preferentially into the tourmaline structure (Al, Mg, Zn), whereas incompatible Mn accumulates, leading to the formation of Mn-rich helvine-danalite. In contrast, beryl only occurs in pegmatites where early-formed tourmaline is absent. The early crystallisation of tourmaline might thus affect the species and composition of later crystallising minerals.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10505 - Geology

Project

<a href="/en/project/EF16_026%2F0008459" target="_blank" >EF16_026/0008459: Long-term research of geochemical barriers for nuclear waste disposal</a><br>

Continuities

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Mineralogical Magazine

ISSN

0026-461X

e-ISSN

1471-8022

Volume of the periodical

89

Issue of the periodical within the volume

6

Country of publishing house

GB - UNITED KINGDOM

Number of pages

13

Pages from-to

913-925

UT code for WoS article

001645336000019

EID of the result in the Scopus database

2-s2.0-105014775442