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 + FeT) 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.

中文翻译：

---

来自阿根廷圣路易斯南锡绿柱石-铌铁矿-磷酸盐花岗岩伟晶岩的富含 Ta、Ti 的氧化物矿物组合

钽铁矿-(Mn)、钽铁矿金红石、珍珠岩-(Fe)、钛白云母、铁氧钛白云母和羟基钙微晶石的组合出现在阿根廷圣路易斯山脉的南希花岗岩伟晶岩中。LCT (Li-Cs-Ta) 稀有元素伟晶岩的 Nancy 绿柱石型绿柱石-铌铁矿-磷酸盐亚型位于古生代 Conlara 伟晶岩油田。组合发生在伟晶岩的核心边缘，形成不规则形状的 18 x 6 厘米结核。钽铁矿-(Mn) 的化学成分显示中值 Ta# [= (Ta/(Ta + Nb) apfu (atoms per formula unit)] 和 Mn# [= (Mn/(Mn + FeT) apfu] 值为 0.57 和分别为 0.64；Ti、U 和 Zr 显示的最大和 [中值] 含量为：3.37 [1.25] wt.% TiO2、0.58 [0.24] wt.% UO2 和 0.72 [0.50] wt.% ZrO2。参数表示中等有序的结构。钽铁矿金红石作为与羟基钙微晶石相关联的钽铁矿-(Mn) 代替面体晶粒出现。其化学成分显示出中等至高的 Ti 含量，最大和 [中值] 为 64.77 [38.67] wt.% TiO2。Ta 的比例非常高，为 49.67 [39.59] wt.% Ta2O5。Tapiolite-(Fe)，含有 82.49 [81.86] wt.% Ta2O5、2.51 [2.33] wt.% Nb2O5、0.94 [0.79] wt.% TiO2 和 13.31 [13.18] wt.% FeO，具有均匀的 Ta# 和 Mn # 值，分别为 0.95 和 0.09。Titanowodginite 显示的 Ta# 值范围为 0.82 至 0.88，而在 ferrotitanowodginite 中其范围为 0.88 至 0.94。Mn# 值在钛白云母中相似 (0.51–0.64)，在铁钛白云母中降低 (0.04 到 0.41)。这些矿物形成钽铁矿-(Mn) 的替代序列。羟基钙微石出现在两代：I 和 II。主要的 A 阳离子是 Ca，CaO 的中值为 14.39 wt.%。MnO 含量的中位数为 1.16 wt.% MnO，相对稳定。UO2 的量通常低于 3 wt.%，但局部达到 6.9 wt.%，特殊情况下达到 43.6 wt.%，在不规则边缘显示出较低的分析总量，给出了偏离预期化学计量的成分；它显然是一个亚固相。在对这种组合演化的更合理的解释中，在早期亚固相线阶段，钽铁矿-（Mn）的岩浆结晶被钽金红石 + 珍珠岩-（Fe） + 钛白金矿 + 铁钛白金矿部分取代，与羟基钙微晶石 I 相关，后来，由可能从围岩进入伟晶岩的晚期含 Fe-Ti-Ca 流体相的流入产生的羟基钙微石 II。