Zaraisky et al. (2010) determined the solubility of Ta 2 O 5 and Ta-bearing columbite in F− -, Cl − -, HCO 3− -, and CO 32 − -bearing solutions at 300–550 °C. The presence of F − increased the solubility of both phases by several orders of magnitude, indicating formation of F- or OH–F-bearing aqueous complexes.

The patchy zoning is the most common texture of CGM in the Bugarura-Kuluti. It is often produced when columbite-tantalite is subjected to an alteration by later fluids (Tindle and Breaks, 2000). Usually, an early columbite generation is replaced (or partially replaced) by a later columbite-tantalite generation richer in Ta (Fig. 8 a–c).

Apatite exhibits textural and compositional evolutionary trends from early-to-late stages of carbonatite evolution. ... Scandium-bearing columbite - tantalite and ixiolite show similar ranges in ...

This study reveals that columbite-tantalite in the pegmatites has an extremely wide range of composition from primitive ferrocolumbite to evolved, almost end-member …

Tantalite is the tantalum-rich member, and Columbite is the niobium-rich member. Tantalite is named after its tantalum content, and, together with Columbite, are the most important minerals containing the rare element tantalum. The name Tantalite has been discredited by the IMA, with the more specific designations of Tantalite- (Fe) (also …

Columbite is a black, crystalline mineral group, and the main ore of niobium which is also called columbate, niobite, and niobite-tantalite [ (Fe, Mn)Nb2O6], it is also a niobate of iron and manganese. It is found in granite, pegmatites, and placer deposits together with tantalite, but has less density. Columbite has the same mineral structure ...

Due to the removal of calcium from the melt by apatite crystallization, microlite and pyrochlore did not recrystallize at the same Ca/Na ratio thus equilibrium cannot be demonstrated, although given that equilibrium was attained for columbite-(Mn), tantalite-(Mn), titanowodginite, and wodginite, it was likely also attained for pyrochlore and ...

The columbite-tantalite commonly exhibits a mottled or patchy zoned texture with the rims consistently higher in Ta than the cores, reflecting the later effect of a …

23 Columbite-tantalite ages from 14 Nb–Ta deposits in South China were reported. • Five distinct Nb–Ta mineralisation events (424–391, 248–204, 160–150, ∼130, and ∼90 Ma) in South China were revealed.

Compositionally, columbite-tantalite of the Li-albite granites is constrained between MnNb 2 O 6 and MnTa 2 O 6 (the Ta/(Nb+Ta) atom. ratio ranges between 0.10 and 0.80). This low to high ratio and the association of columbite-tantalite with topaz, fluorite and lithian micas (in the series zinnwaldite-white mica) indicate a higher solubility ...

It is advisable to use columbite of textural relation with primary phases in the host pegmatite to obtain an accurate date of the primary columbite generation, because columbite U-Pb age data from ...

Subhomogeneous cores of columbite-(Fe)−tantalite-(Fe) (A) are surrounded by heterogeneous intermediate zones (B) and (C) with irregular to oscillatory zoning and mutually comparable compositions.

Columbite-tantalite minerals are potentially useful for dating the emplacement age of economically important rare-element pegmatites. Romer and Wright have shown that columbite-tantalite may accommodate considerable amounts of uranium (circa 500–1000 ppm) and exclude lead almost completely.The U-Pb systematics, …

Tantalite's greatest difference from columbite is its much higher specific gravity, 8.0+ compared to columbite's 5.2. Other properties that vary slightly are color, transparency and streak. Both minerals can be found more or less together in granitic pegmatites rich in lithium and phosphorus minerals with columbite concentrated at the edges of ...

Wolfram is a typomorfic impurity in columbite–tantalite of the Kester Deposit, WO 3 is 1.77%, on average (apfu is 0.03). In tantalite- (Mn), WO 3 is 0.70%, while in columbite- (Fe), WO 3 is 2.67%, reaching 7.12%. The wolfram impurity is more typical for columbite, whereas the tin impurity is typomorphic for tantalite: the average content of ...

actinolite-tremolite, apatite, ferroan dolomite, erythrite, galena, ilmenite, magnetite, talc Briar Fork-near Schuyler (excavation on Rt. 6) ... Columbite-tantalite crystal; 1% by 1 by 3/4 inch; Mitchell mine, Bedford County. Photograph by …

Columbite-tantalite mineralisation in pegmatites in Burundi has been dated at 962 ± 2 Ma and 968 + 33/ 29 Ma (U–Pb dating columbite-tantalite grains; Romer and Lehmann, 1995). The granite–pegmatite …

LCT (lithium–cesium–tantalum) pegmatites from the Kaustinen and Kolmozero regions contain columbite–tantalite mineralization, which has been presented in this study. Crystal structure, Raman microscopy, and optical property analyses of these minerals were performed. As a result of the structural studies and micro-area analyses, it was …

Columbite-tantalite minerals are potentially useful for dating the emplacement age of economically important rare-element pegmatites. Romer and Wright …

Columbite-tantalite minerals commonly have a broad range of U contents that may reach several thousand ppm and may substitute for Fe and Mn into the crystal lattice, but for high U contents may form phases of its own (e.g., uraninite; cf. Romer et al., 1996). Furthermore, columbite-tantalite minerals typically have very low common Pb …

Abstract. Compositional variation (results of electron microprobe analyses and mass-spectrometry analyses) of columbite-group minerals (CGM) from fully …

The pegmatites of the Gatumba area (western Rwanda) have historically been mined for their columbite-tantalite and cassiterite mineralisation, but contain also beryl, apatite, spodumene ...

Two contact-parallel micro-layers of apatite are visible in (b); bright grains are columbite–tantalite. (c, d and e) Typical BZ assemblage with quartz, acicular tourmaline, microcline, albite, skeletal or radiating muscovite, …

The zoned pegmatite is variably mineralised in columbite-tantalite and/or cassiterite with accessory minerals, including apatite, beryl, spodumene, tourmaline, amblygonite and rare phosphate minerals. The Gatumba area consists of Mesoproterozoic rocks, which belong to the lithostratigraphic Akanyaru Supergroup .

Columbite has the same composition and crystal symmetry (orthorhombic) as tantalite. In fact, the two are often grouped together as a semi-singular mineral series called columbite-tantalite or coltan in many mineral guides. However, tantalite has a much greater specific gravity than columbite, more than 8.0 compared to columbite's 5.2.

@article{Che2019EpisodicNM, title={Episodic Nb–Ta mineralisation in South China: Constraints from in situ LA–ICP–MS columbite-tantalite U–Pb dating}, author={Xudong Che and Rucheng Wang and Fu-Yuan Wu and Ze-Ying Zhu and Wenlan Zhang and Huan Hu and Lei Xie and Jian-Jun Lu and Di Zhang}, journal={Ore Geology Reviews}, …

The increased demand of metals such as tantalum (Ta) and niobium (Nb) reflect the on-going development in modern science, engineering and technology. The extraction of these two metals from columbite-tantalite ore is based on generic extractive metallurgy. However, the upstream purification of ore and downstream extraction of Ta …

Abstract. Columbite–tantalite (Coltan) is the most important niobium (Nb)- and tantalum (Ta)-bearing economic mineral, commonly occurring in rare metal granite and pegmatite, alkaline granite, syenite and carbonatite. Its high U but low common Pb contents make it an ideal mineral for U–Pb isotopic dating of Nb–Ta mineralization.

Columbite is the niobium-rich member, and Tantalite is the tantalum-rich member. Columbite is named after its niobium content, which was previous known as columbium prior to its renaming. Columbite is the most important mineral containing the rare element niobium and is its main ore. The name Columbite has been discredited by the IMA, with …