Columbite-tantalite group minerals (CGMs) are important sources of critical elements, i.e., ... in the study area within the QM or even within the NQTB are similar to the major metallogenic stages of the …

Mn-rich members of the columbite-group minerals (CGM) are the most common Ta-bearing phases, but microlite, wodginite, tapiolite and Ta-rich cassiterite occur also. …

Here, we report on new U–Pb age data from columbite-tantalite minerals and 40 Ar– 39 Ar age data on muscovite from the Gatumba area in Rwanda, forming part of the KAB (Fig. 2).The study area is situated in the western part of Rwanda, about 50 km west of Kigali and can be considered as representative of pegmatite mineralisation in the …

Mineralogy and chemistry of columbite-tantalite from Bugarura-Kuluti area, Karagwe-Ankole Belt, Rwanda: indicators of pegmatite and granite evolution ... This investigation shows that the composition of the nucleating phases can be approximated using classical nucleation theory, that the oscillatory zoning is not solely controlled by the ...

Columbite-group minerals with 1-3 wt.% Sc2O3 are referred to as scandian columbite - tantalite and show degrees of structural order similar to columbite - tantalite lacking Sc. Disordered ...

Replacement of columbite by at least two later columbite-tantalite phases, BE1. Lower part shows X-ray line profiles illustrating the variation in Ta and Mn between points A and F. The letters refer to analyses 8 A-F. zoning of columbite-tantalite, the concentration and diffusion of Ta and and the growth dynamics of columbite …

Towards sustainable processing of columbite group minerals: elucidating the relation between dielectric properties and physico-chemical transformations in the …

Extraction of Niobium and Tantalum Oxides From Columbite Concentrate Using Microwave Processing and Solvent Extraction. Original Research Article. …

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.

The chemical reaction of columbite and tantalite with KOH at elevated temperatures leads to the formation of K 3 NbO 4 and K 3 TaO 4 phases, as illustrated in chemical reaction Eq. . These phases undergo hydrolysis upon reaction with water and are transferred into the aqueous solution based on the reaction presented in Eq. . Thermal …

New data on rare earth element (REE) concentrations and distribution patterns of columbite-tantalite minerals from Ta-ore provinces worldwide are presented. The REE geochemistry was studied by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Five major types of chondrite-normalized REE distribution patterns are …

ETDEWEB / / REE geochemistry of uranium-bearing columbite-tantalites and multiple oxide phases from proterozoic rare metal pegmatites of Pandikimal and ... Orissa have been studied and evaluated. Columbite-tantalite from these areas contain low {sigma}REE (100-1000 ppm)with LREE/HREE{sub CN}<0.5 and minor amounts of …

Such phases can be recovered as a by-product of mining for other economic minerals like columbite-tantalite, beryl, mica, lithium minerals, feldspars, quartz. This exercise may prove quite rewarding.

These anomalous compositions are connected with external parts of the columbite to tantalite crystals (Fig. 5f) and these phases represent a part of the same columbite to tantalite evolutionary trend with a rapid …

Columbite-tantalite, cassiterite and other Ta-Nb-Sn oxides in sediments from catchments that contain known LCT pegmatite occurrences show the same textural and chemical characteristics as these ...

The XRPD pattern in Fig. 1 shows that the major phases present in the mineral are ferro-columbite (n°1) and tapiolite (n°3), whereas muscovite (n°5), nacrite (n°4) and free silica (n°2) are ...

Rare earth element (REE) geochemistry of uranium bearing columbite-tantalite and multiple Nb-Ta oxide phases from the Pandikimal-Jangapara pegmatites, Jharsuguda district, Orissa have been studied and evaluated columbite-tantalite from these areas contain low ∑REE (100-1000 ppm) with LREE/HREE CN LREE. Plot of …

Li-mineralized pegmatites underwent magmatic and post-magmatic stages. ... New U–Pb dating CGMs (columbite-tantalite group minerals) in five zones have a consistent age (380 ± 10 Ma). Whilst U–Pb dating of apatite and cassiterite from different structural zones show remarkable two group isotopic ages (370–390 Ma and 145–160 …

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 …

Minerals from the columbite-tantalite series are the most common Nbtantalates found in granitic pegmatites, mainly occurring as solid solutions. ... The chemical composition of these phases is ...

Columbite-(Fe) in tabular crystal from the Nine Mile pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.) Columbite-tantalite refers to a group of minerals having varying amounts of iron, manganese, niobium, and tantalum. They are found as platey black grains in complex granitic pegmatites. …

Columbite-tantalite-bearing granitic pegmatites from the Seridó Belt, northeastern Brazil: Genetic constraints from U-Pb dating and Pb isotopes ... Li–Be, and Li–Cs–Be–Ta phases ...

Columbite-group minerals occur in all main parageneses of the pegmatites and form four generations, reflecting the sequence of pegmatite formation. These …

that was present between the quartz grains and the columbite-tantalite mineral. It did not react with the mineral grains of the columbite group. The ultrastructure of the columbite-tantalite mineral suggested the columbite-group mineral in the Zhaojinggou Nb-Ta deposit formed during magmatic crystallization rather than from hydrothermal fluids.

The dissolution of a tantalite/columbite concentrate was substantially affected by milling for an extended period. Dry milling was found to be more effective than wet milling, despite the latter attaining a somewhat greater surface area due to the prevention of agglomeration. A powder dry milled for 50 h showed a dissolution rate over …

Bolded are dominant phases. FeC = columbite-(Fe); FeT = tantalite-(Fe); MnC = columbite-(Mn); MnT = tantalite-(Mn); Tap = tapiolite; Wdg = wodginite; CGM = columbite-group minerals.

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.

Most of the minor mineral phases occur as small inclusions in columbite–tantalite and consist of cassiterite, zircon, struverite and microlite group …

Major progress has been made in the direct dating of metal-bearing phases (such as wolframite, cassiterite, columbite-tantalite or sulfides, notably molybdenite) in recent years, through both ...

Evidence of the saturation of columbite-tantalite was not attained; if it had been, a depletion in Ta contents would have occurred once this mineral phase reached its saturation, as CGM contain Ta, an essential structural constituent (ESC) in these mineral phases (López Moro et al., Reference López Moro, García Polonio, Llorens González ...