Wodginite as an indicator mineral of tantalum-bearing pegmatites and granites

Abstract

In the composition of tantalum-niobates the tin-bearing wodginite group minerals (WGM) were found: wod-ginite, titanowodginite, ferrowodginite, ferrotitanowodginite, lithiowodginite, tantalowodginite, “wolframowodginite”. We reviewed the worldwide research on WGM and created a database of 698 analyses from 55 sources including the author's data. WGM are associated with Li-F pegmatites and Li-F granites. Wodginite is the most prevalent mineral, occurring in 86.6 % of pegmatites and 78.3 % of granites. The occurrence of WGM in granites and pegmatites differs. For instance, titanowodginite and “wolframowodginite” occur three times more frequently in granites than in pegmatites, whereas lithiowodginite and tantalowodginite do not appear in granites at all. The difference between WGM in granites and pegmatites is in finer grain size, higher content of Sn, Nb, Ti, W, and Sc; lower content of Fe3+, Ta, Zr, Hf; higher ratio of Mn/(Mn + Fe); and lower ratio of Zr/Hf. The evolutionary series of WGM in pegmatites are as follows: ferrowodginite → ferrotitanowodginite → titanowodginite → “wolframowodginite” → wodginite → tantalowodginite; in granites: ferrowodginite → ferrotitanowodginite → “wolframowodginite” → wodginite → titanowodginite. WGM can serve as indicators of tantalum-bearing pegmatites and granites. In Russia the promising sources of tantalum are deposits of the Far Eastern belt of Li-F granites containing wodginite.

The Presence of Wodginite in Lithium–Fluorine Granites as an Indicator of Tantalum and Tin Mineralization: A Study of Abu Dabbab and Nuweibi Massifs (Egypt)

“…The combination of different mineral species of the same elements, the abundance of mineral inhomogeneities, and the variety of impurity elements indicate a long history of mineralization and the geochemical richness of ore sources, which is typical of large deposits of mineral raw materials. The study of wodginite in the LFGs of eastern Egypt confirms the previous conclusion that wodginite is an indicator of ore-bearing granites and associated tantalum and tin mineralization [14]. For example, the presence of wodginite with similar characteristics in alluvial deposits is an indicator of the native tin and tantalumbearing LFG and greisens.…”

“…Wodginite from the Nuweibi LFG is compositionally similar to wodginite described in other locations [14], but with a lower TiO 2 content, averaging at 0.54%; Ti/(Sn + B Ta + Ti + Fe 3+ ) = 0.04 (Table 1; Figure 4a-c). The empirical formula of Nuweibi wodginite is (Mn 2+ 0.75 Fe 2+ 0.25 ) The representative electron probe microanalysis and average composition (Av.)…”

“…Three forms of wodginite crystallization are identified in the LFG, from which wodginite rims in the accessory tantalite and autonomous wodginite crystals (Figures 2a-c,f and 3a,b,d) indicate the metasomatic replacement of tantalite-(Mn) by wodginite in the presence of a late-magmatic fluid phase [14,41]. The inclusion of wodginite in pegmatite cassiterite led researchers to conclude that they formed during the breakdown of the solid solution "cassiterite-tantalum-niobates" [42].…”

“…In these granites, these minerals have small sizes (1-100 µm), and they do not include lithiowodginite or tantalowodginite. Titanowodginite occurs three times more frequently in LFGs than in pegmatites [9,13,14].…”

“…Wodginite diagnostics were performed based on the work in [16][17][18] and the latest review of the mineralogy of the wodginite group [14]. The data were statistically processed taking into account the content distribution of the components [19].…”