A Ta,Ti-rich oxide mineral assemblage from the Nancy beryl-columbite-phosphate granitic pegmatite, San Luis, Argentina

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F19%3A00113463" target="_blank" >RIV/00216224:14310/19:00113463 - isvavai.cz</a>

Result on the web

<a href="https://link.springer.com/article/10.1007/s00710-019-00673-z#Ack1" target="_blank" >https://link.springer.com/article/10.1007/s00710-019-00673-z#Ack1</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s00710-019-00673-z" target="_blank" >10.1007/s00710-019-00673-z</a>

Result language

angličtina

Original language name

A Ta,Ti-rich oxide mineral assemblage from the Nancy beryl-columbite-phosphate granitic pegmatite, San Luis, Argentina

Original language description

An assemblage of tantalite-(Mn), tantalian rutile, tapiolite-(Fe), titanowodginite, ferrotitanowodginite, and hydroxycalciomicrolite occurs in the Nancy granitic pegmatite, San Luis range, Argentina. The Nancy beryl-type, beryl-columbite-phosphate subtype of LCT (Li-Cs-Ta) rare-element pegmatite was emplaced in the Paleozoic Conlara pegmatitic field. The assemblage occurs at the core margin of the pegmatite, forming an irregularly shaped, 18 by 6 cm nodule. The chemical composition of tantalite-(Mn) shows median Ta [= (Ta/(Ta + Nb) apfu (atoms per formula unit)] and Mn [= (Mn/(Mn + Fe-T) apfu] values of 0.57 and 0.64, respectively; Ti, U and Zr show maximum and [median] contents of: 3.37 [1.25] wt.% TiO2, 0.58 [0.24] wt.% UO2, and 0.72 [0.50] wt.% ZrO2. The unit-cell parameters indicate a moderately ordered structure. Tantalian rutile occurs as anhedral grains replacing tantalite-(Mn), associated with hydroxycalciomicrolite. Its chemical composition shows moderate to high Ti contents, with a maximum and [median] of 64.77 [38.67] wt.% TiO2. The proportion of Ta is very high, with 49.67 [39.59] wt.% Ta2O5. Tapiolite-(Fe), with 82.49 [81.86] wt.% Ta2O5, 2.51 [2.33] wt.% Nb2O5, 0.94 [0.79] wt.% TiO2, and 13.31 [13.18] wt.% FeO, has uniform Ta and Mn values, 0.95 and 0.09, respectively. Titanowodginite shows Ta values ranging from 0.82 to 0.88, whereas in ferrotitanowodginite it ranges from 0.88 to 0.94. The Mn value is similar in titanowodginite (0.51-0.64), and decreases in the ferrotitanowodginite (0.04 to 0.41). These minerals form a replacement sequence of tantalite-(Mn). Hydroxycalciomicrolite occurs in two generations: I and II. The dominant A cation is Ca, with a median value of 14.39 wt.% CaO. The MnO content, with a median of 1.16 wt.% MnO, is relatively constant. The amount of UO2 is usually below 3 wt.%, but locally attains 6.9 wt.%, and exceptionally 43.6 wt.%, in irregular rims that show a low analytical total, giving compositions that depart from the expected stoichiometry; it is clearly a subsolidus phase. In the more plausible explanation for the evolution of this assemblage, the magmatic crystallization of tantalite-(Mn) was followed during the early subsolidus stage by its partial replacement by tantalian rutile + tapiolite-(Fe) + titanowodginite + ferrotitanowodginte, associated with hydroxycalciomicrolite I, and later, by hydroxycalciomicrolite II produced by the influx of a late Fe-Ti-Ca-bearing fluid phase likely entering the pegmatite from the wall rocks.

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

10504 - Mineralogy

Project

<a href="/en/project/7AMB14AR006" target="_blank" >7AMB14AR006: Granitic pegmatites from Argentina and Czech Republic; indicators of geological evolution as well as sources of ?high-tech? elements</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2019

Confidentiality

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

Name of the periodical

Mineralogy and Petrology

ISSN

0930-0708

e-ISSN

—

Volume of the periodical

113

Issue of the periodical within the volume

5

Country of publishing house

AT - AUSTRIA

Number of pages

15

Pages from-to

687-701

UT code for WoS article

000485902500008

EID of the result in the Scopus database

2-s2.0-85068843096