Experimental studies of Ta2O5 and columbite–tantalite …
However, columbite–tantalite solubility increases with increasing temperature in KF solutions and it remains constant in HCl solutions. According to our experimental data over all investigated range of temperatures, ... Linnen RL (1998) The solubility of Nb–Ta–Zr–Hf–W in granitic melts with Li and Li+F: constraints for …
Composition of complex lepidolite-type granitic pegmatites …
Uranmicrolite is restricted to the purple lepidolite zones, and columbite-tantalite is more Mn-rich than in granites. The Mn/(Fe+Mn) value actually varies over a narrow range (+ or -0.01) within each sample, but the variation between different bodies of pegmatite (from 0.90 to 0.96 and 0.99) again suggests multiple intrusions.
Columbite Tantalite: a film that fuses Congo's past and …
In full, coltan's name is columbite-tantalite, after Tantalus, the figure in Greek mythology who was condemned to a horrifying eternal torment, of the things he most desired being just out of his ...
Columbite: The mineral columbite-tantalite information …
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 …
Late Neoproterozoic over of the cassiterite and columbite …
Highlights The Mesoproterozoic Kibara belt in Central Africa contains Nb–Ta–Sn mineralised pegmatites and Sn–W mineralised quartz veins. Nb–Ta mineralisation formed during crystallisation of the pegmatites, while Sn–W mineralisation during metasomatic alteration. U–Pb ages of columbite-tantalite samples vary between …
Columbite Group: Mineral information, data and localities.
[Tantalite-(Fe)] Walter, F. (1998): Exkursion E4 am 27.9.1998 - MinPet 98 (Pörtschach am Wörthersee/Kärnten) - Die Pegmatite des Millstätter See-Rückens. Mitt. ... Yang, Bingzhang Wang, Tong Pan, Jie Han, Hongliang Cao, Yan Tang, and Liangliang Zhang. (2023) "Age and Composition of Columbite-Tantalite Group Minerals in the Spodumene ...
(PDF) Compositional, structural and phase …
... Minerals from the columbite-tantalite series are the most common Nbtantalates found in granitic pegmatites, mainly occurring as solid solutions. Their generic formula is AB 2 O 6,...
U-Pb isotopic dating of columbite-tantalite minerals: Development of
The different columbite-tantalite minerals are available to the scientific community, depending of the quantity available for each reference material. The U-Pb dating of columbite-tantalite minerals by SIMS demonstrates that there are major matrix effects that mainly depend on the Nb/Ta ratio of the columbite-tantalite minerals.
Chemistry of columbite-tantalite minerals in rare …
December 1998. DOI: 10.1180/002646198548197. Bibcode: 1998MinM...62..821A. Paragenetic, textural, and chemical characteristics of columbite-tantalite minerals are …
Experimental studies of Ta2O5 and columbite–tantalite …
The dependence of columbite–tantalite (Nb2O5-59 wt. %, Ta2O5-18 wt. %) solubility as a function of solution composition, T, and P has also been investigated. Tantalum and Nb concentrations have the highest values in HF solutions at reduced conditions (up to 10−3 to 10−2 m Ta in 1 m HF). ... 1998; Tantalum mineralization is …
(PDF) Analytical fingerprint of columbite-tantalite (coltan
columbite-tantalite solid solution series (abbreviated CGM, columbite-group minerals). Such concentrates contain from ten. ... the outbreak of the Congolese war in 1998, mining, distrib ution.
Chemistry of columbite-tantalite minerals in rare metal …
Paragenetic, textural, and chemical characteristics of columbite-tantalite minerals are examined as steps towards identifying the metallogenetic processes of their host granitoids. Columbite-tantalite-bearing granitoids of the Eastern Desert province of Egypt can be categorized into: (i) metaluminous alkali granites; (ii) peraluminous Li-albite granites; and …
Enhanced dissolution of tantalite/columbite following milling
No other reagent has the capacity to solubilise the tantalite/columbite ore within an economically viable time. A number of mineral systems have shown that the leaching rate can be enhanced by milling Balaz et al., 1996, Fletcher and Welham, 2000, Welham, 1997, Welham and Llewellyn, 1998, the enhancement being greater than that …
Columbite-Tantalite – WGNHS – UW–Madison
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. …
Finger of conflict minerals: columbite-tantalite ("coltan") ores
Combined mineralogical-geochemical-geochronological signatures of columbite-tantalite ores are used to trace the origin of ore concentrates. ... al., 1996; Wise et al., 1998). Coupled sub ...
Columbite-tantalite mineral chemistry from rare …
Columbite-tantalite group minerals are ubiquitous in beryl-, complex-, albite-spodumene- and albite-type rare-element pegmatites. Consequently, many authors ... 1998; Tindle et al., 1998). To date, less Columbite-tantalite mineral chemistry from rare-element granitic pegmatites 167. Fig. 1. General geology of the Separation Lake metavolcanic ...
Mineral chemistry of columbite–tantalite from
Abstract. Compositional variation (results of electron microprobe analyses and mass-spectrometry analyses) of columbite-group minerals (CGM) from fully …
Micas, feldspars and columbite–tantalite minerals from …
The Namivo granitic lepidolite-subtype pegmatite is concentrically zoned. Textural and chemical studies show at the crystal scale and within each zone that muscovite evolved to lithian muscovite ...
Scandium substitution in columbite-group minerals and …
The Canadian Mineralogist 1998;; 36 (2): 673–680. doi: Download citation file: Ris (Zotero) Refmanager; EasyBib; Bookends; Mendeley; Papers; ... Columbite-group minerals with 1-3 wt.% Sc 2 O 3 are referred to as scandian columbite-tantalite and show degrees of structural order similar to columbite-tantalite lacking Sc. Disordered …
Columbite-tantalite-bearing granitic pegmatites from the …
These compositions are compatible with the mineralizations of apatite, beryl, columbite-tantalite, spodumene, lepidolite, tourmaline, monazite, gahnite and phosphate group minerals observed in the ...
Original paper Complex magmatic and subsolidus …
1998). At Šejby, N–S trending dikes of albite–muscovite pegmatitic granite with accessory biotite, topaz, garnet, fluorapatite and columbite–tantalite cut the Weinsberg granite and the surrounding migmatized paragneisses (Matějka and Klečka 1994; Breiter and Scharbert 1998). The exposed pegmatites form zoned N- to S-trending
The key role of mica during igneous concentration of …
In pegmatites, Nb–Ta fractionation is often attributed to the crystallization of columbite–tantalite [(Mn 2+, Fe 2+) (Ta, Nb) 2 O 6] (Linnen and Keppler 1997; Linnen 1998; Chevychelov et al. 2010; Černý et al. 2012). Muscovite also has been implicated as a mineral able to fractionate Ta from Nb (Kovalenko et al. 1996; Raimbault and Burnol ...
Compositional variations in ferrotapiolite + tantalite pairs …
Three texturally and compositionally distinct pairs of ferrotapiolite+tantalite, all spatially related to a cleavelandite unit, were distinguished in the zoned beryl-columbite pegmatite at ...
Columbotantalite (cbt/coltan) | SpringerLink
The generic term columbotantalite, cbt, comprises the different compositional varieties of columbite and tantalite, classically treated (e.g. Ramdohr 1980) as an isomorphic, continuous solid solution series between the members (Fe, Mn)Nb 2 O 6 (niobite, now columbite, cb) and (Fe, Mn)Ta 2 O 6 (tantalite, tan), a series also known …
Effects of fluorine on the solubilities of Nb, Ta, Zr and Hf …
The effect of fluorine on the solubilities of Mn-columbite (MnNb 2 O 6), Mn-tantalite (MnTa 2 O 6), zircon (ZrSiO 4) and hafnon (HfSiO 4) were determined in highly fluxed, water-saturated haplogranitic melts at 800 to 1000 °C and 2 kbar. The melt composition corresponds to the intersection of the granite minimum with the …
Mineralogy and chemistry of columbite-tantalite from …
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).
(PDF) Columbite-tantalite mineral chemistry from rare
Columbite-tantalite mineral chemistry from rare-element granitic pegmatites: Separation Lake area, N.W. Ontario, Canada ... (1998), although. evidence of localized . phosphorus (and . fluorine ...
Metallographic and in situ compositional study on columbite–tantalite
The main compositions identified are columbite-(Mn) and columbite-(Fe), but Fe- and Mn-tantalites are also important minerals as well as ixiolite–wodginite. Most of the minor mineral phases occur as small inclusions in columbite–tantalite and consist of cassiterite, zircon, struverite and microlite group minerals.
Tantalum (Ta) [Z = 73]
The columbite group is a solid solution with varying proportions of Nb or Ta in its composition. According to the International Mineralogical Association (IMA), 'tantalite' or 'coltan' are not scientific names, yet they are widely used. Many specimens commonly named tantalite are actually minerals of the columbite or tapiolite group ...
Scandium substitution in columbite-group minerals and ixiolite
In most pegmatites, Sc fractionation in columbite-tantalite, stannian ixiolite, titanian ixiolite and wolframian ixiolite is erratic, unlike scandian ixiolite, which shows …
