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@article{1641677,
author = {Galliski, M.A. and MarquezandZavalia, M.F. and Škoda, Radek and Novák, Milan and Čopjaková, Renata and Pagano, D.S.},
article_location = {WIEN},
article_number = {5},
doi = {http://dx.doi.org/10.1007/s00710-019-00673-z},
keywords = {Tantalite-(Mn); Tantalian rutile; Wodginite-group minerals; Hydroxycalciomicrolite; Rare-element granitic pegmatite; Sierras Pampeanas; Argentina},
language = {eng},
issn = {0930-0708},
journal = {Mineralogy and Petrology},
title = {A Ta,Ti-rich oxide mineral assemblage from the Nancy beryl-columbite-phosphate granitic pegmatite, San Luis, Argentina},
url = {https://link.springer.com/article/10.1007/s00710-019-00673-z#Ack1},
volume = {113},
year = {2019}
}
TY - JOUR
ID - 1641677
AU - Galliski, M.A. - Marquez-Zavalia, M.F. - Škoda, Radek - Novák, Milan - Čopjaková, Renata - Pagano, D.S.
PY - 2019
TI - A Ta,Ti-rich oxide mineral assemblage from the Nancy beryl-columbite-phosphate granitic pegmatite, San Luis, Argentina
JF - Mineralogy and Petrology
VL - 113
IS - 5
SP - 687-701
EP - 687-701
PB - Springer Wien
SN - 09300708
KW - Tantalite-(Mn)
KW - Tantalian rutile
KW - Wodginite-group minerals
KW - Hydroxycalciomicrolite
KW - Rare-element granitic pegmatite
KW - Sierras Pampeanas
KW - Argentina
UR - https://link.springer.com/article/10.1007/s00710-019-00673-z#Ack1
L2 - https://link.springer.com/article/10.1007/s00710-019-00673-z#Ack1
N2 - 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.
ER -
GALLISKI, M.A., M.F. MARQUEZ-ZAVALIA, Radek ŠKODA, Milan NOVÁK, Renata ČOPJAKOVÁ a D.S. PAGANO. A Ta,Ti-rich oxide mineral assemblage from the Nancy beryl-columbite-phosphate granitic pegmatite, San Luis, Argentina. \textit{Mineralogy and Petrology}. WIEN: Springer Wien, 2019, roč.~113, č.~5, s.~687-701. ISSN~0930-0708. Dostupné z: https://dx.doi.org/10.1007/s00710-019-00673-z.
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