Elements In Granite Research Articles

Geology of Rare Metals in Egypt- A review

The term “rare metals” refers in this work to metals with a low availability in natural. Based on their chemistry, rare metals were classified into; 1) rare earth elements (La-Lu), 2) trace elements (Nb, Ta, Mo, Cu, Ni, Co, Sn, W, V), 3) noble elements (Au, Ag, and PGE) and 4) fissionable elements (U and Th). In Egypt, rare earth elements occur in the phosphorites, monazite and granites. Trace elements occur in three associations; a) elements in granites and albite granites such as Nb, Ta, Sn, Mo, and W, b) elements associate mafic rocks and ophiolites include Cu, Ni, and Co, and c) V in the black shales. 95 Au localities were reported mainly as vein-type mineralization in the Eastern Desert. PGE are confined to three associations including mafic and ultramafic rocks, chromite and black shales as sulfides, alloys, and organometallic compounds, respectively. Uranium occurs in granites of the Eastern Desert. Thorium was reported at the Um Ara area at the Eastern Desert and in the monazite from the black sands. Although rare metals are quite common in Egypt, processing and beneficiations of the rare metals-bearing rocks did not reflect the abundance and the economic significance of these metals

Хіміко-аналітичні особливості визначення вмісту рідкісноземельних елементів у складі гранітів методом мас-спектрометрії

Хіміко-аналітичні особливості визначення вмісту рідкісноземельних елементів у складі гранітів методом мас-спектрометрії

Decoupled Ca and Fe + Mg content of S-type granites: An investigation on the factors that control the Ca budget of S-type granites

The compositional variation of S-type granites is thought to derive from source-controlled processes whereby magmas acquire their composition as a result of entrainment of variable proportions of a peritectic-rich residual mineral assemblage into the melt. A corollary of this model is that the entrained phases keep the stoichiometric proportions they have in the partially melted source. These proportions are controlled by the composition of the subsolidus minerals. Consequently, it is expected that the ratio between maficity (FeOt + MgO) and other compatible major elements in granites would be the same as those of the source. This is true for Ti but not for Ca which shows systematically higher Ca:maficity ratios. In order to explore the factors that cause this discrepancy, thermodynamic calculations were used to study the partial melting of a representative metapelite and a metagreywacke under a range of crustal pressure and temperature conditions. The modelling included segregation of melt or magma in pulses, disequilibrium melting of plagioclase (in which only a fraction of this phase participates in the melting system and produces two populations of plagioclase, the unreacted cores with the original, Na-rich composition and a second one with a Ca-rich composition) and the entrainment of up to 40 wt% minerals into the melt. This entrained assemblage consists of two fractions, one containing the minerals that are most likely to be surrounded by melt in the source and representing 80 wt% of the total assemblage, and another one consisting of the phases that are most likely to make up the solid framework, with the minerals within each fraction keeping stoichiometric proportions. The modelled magmas failed to reproduce the observed high Ca:maficity ratios. This indicates that there are other processes that increase the Ca content of granites. Several processes were evaluated, including the presence of apatite, enhanced availability of subsolidus plagioclase in the melting system, disequilibrium Ca-rich melts and enhanced entrainment of Ca-rich plagioclase. The last three processes were found to increase the Ca content but only enhanced entrainment of Ca-rich plagioclase increases the Ca:maficity ratio to values similar to those of the granites. A possible explanation for the preferential entrainment of Ca-rich plagioclase is that the density of this phase is different to that of garnet and ilmenite and similar to the density of the melt. Consequently, a significant fraction of the plagioclase in granites may actually be of residual origin. Other relevant findings of this study are that metagreywackes seem to be the main source of S-type granites, as previous investigations suggested, and that cordierite-rich granitoids represent mineral-rich magmas that are formed only from metapelites at pressures below 0.75 GPa. This investigation emphasizes the importance of source-controlled processes in the composition of S-type granites and indicates that entrainment of a mineral assemblage into the melt is not a simple and straightforward process as previously thought.

Monazite and zircon as major carriers of Th, U, and Y in peraluminous granites: examples from the Bohemian Massif

The chemical compositions of zircon and monazite and the relationships between the contents of Th, U, Y, and REE in both minerals and in the bulk samples of their parental rocks were studied in three Variscan composite peraluminous granite plutons in the Bohemian Massif. It was established that granites of similar bulk composition contain zircon and monazite of significantly different chemistry. Monazite typically contains 5–13 wt% (rarely up to 28 wt%) ThO2, 0.4–2 wt% (up to 8.2 wt%) UO2, and 0.5–2 wt% (up to 5 wt%) Y2O3, whereas zircon typically contains less than 0.1 wt% (rarely up to 1.7 wt%) ThO2, less than 1 wt% UO2 (in the Plechý/Plockenstein granite, commonly, 1–2 wt% and scarcely up to 4.8 wt% UO2), and less than 1 wt% Y2O3 (in the Nejdek pluton often 2–5, maximally 7 wt% Y2O3). Monazite is an essential carrier of thorium, hosting more than 80 % of Th in all studied granites. Monazite also appears to be an important carrier of Y (typically 14–16 %, and in the Melechov pluton, up to 81 % of the total rock content) and U (typically 18–35 % and occasionally 6–60 % of the total rock budget). The importance of zircon for the rock budget of all the investigated elements in granites is lower: 4–26 % U, 5–17 % Y, and less than 5 % Th.

Determination of trace elements in granites by inductively coupled plasma mass spectrometry

Proposed is a simple and reliable method for the dissolution of granite and the determination of 38 elements by inductively coupled plasma mass spectrometry. One hundred milligrams of sample are digested with 1 ml of HF and 0.5 ml of HNO 3 in screw top PTFE-lined stainless steel bombs at 190°C for 12 h. Insoluble residues are dissolved using 8 ml of 40% HNO 3 (v/v) heated to 110°C for 3 h. Six granite standard reference materials (GSR-1, JG-2, G-2, NIM-G, SG-3, SG-1a) were studied. Analytical calibration was accomplished using aqueous standard solutions. Rhodium was used as an internal standard to correct for matrix effects and instrument drift. We report data for: Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cs, Ba, Hf, Ta, W, Pb, Th, U and 14 of the rare earth elements. The recoveries for most of these elements in granite ranged from 90 to 110%.

Determination of Major and Minor Elements in Granite by Inductively Coupled Plasma and X-ray Fluorescence Spectrometry

Abstract The development and evaluation of an analytical method for the determination of major and minor elements in granite by ICP-AES and XRF are described. The method applies a standard addition method to generate calibration standards for XRF measurements by ICP-AES from samples to be analyzed. Reliable results were obtained by using simple versions of ICP and XRF, and combined with the pressed-powder pellets for sample preparation. Least squares data for parameters measured by this method vs. reported value for a granite standard reference material gave a slope of 1.002 ± 0.005 and an intercept of -0.029 ± 0.07. The coefficients of variation vary between 0.53% for the largest oxide and 8.3% for the lowest oxide.

Uranium and selected trace elements in granites from the Caledonides of East Greenland

AbstractThe Caledonian fold belt of East Greenland contains calc-alkaline granite(sensu lato)intrusions with ages ranging fromc.2000 Ma toc.350 Ma. The Proterozoic granites have low U contents and the pre-Devonian Caledonian granites contents of U corresponding to the clarke value for U in granites. Some aspects of the geochemistry of U are discussed using U-K/Rb, U-Sr, U-Zr, and U-Th diagrams. Secondary enrichment and mineralization occurs in fractured and hydrothermally altered granites and rhyolites situated in or near a major NNE fault zone. The U is associated with iron oxides or hydrocarbons. It is suggested that the source of the mineralization was Devonian acid magma, which also acted as a heat source for circulating hydrothermal fluids.

Instrumental neutron activation analysis and the characterization of granitic rocks

It has been shown that instrumental neutron activation analysis with intermediate to long-lived isotopes can be used to determine 25 elements in granites from the Bushveld Igneous Complex, South Africa. By the use of the multivariate technique of discriminant analysis these element concentrations were used to characterize the mineralized granite. The results indicate that because of its ability to determine elements influenced by the process of differentiation, as well as incompatible elements, such as Ta, Th and the heavy rare earths, this method provides a powerful tool for the characterization of granitic rocks.

Neutron-activation analysis by standard addition and solvent extraction. Determination of some trace elements in granite and diabase rocks

A rapid procedure is presented for the determination of scandium, thorium, cobalt, iron, silver, zinc, and mercury in granite and diabase rocks by neutron-activation analysis. The induced 233pa, 60Co, 59Fe, 110Ag, 65Zn, and 203Hg are extracted with tridodecyl amine (TDA), while 46Sc is then separated with tributyl phosphate (TBP). The extracted isotopes are sequentially eluted from the TDA extracts with various acidic solutions; 233Pa and 60Co contained in one of the fractions are subsequently separated by the selective extraction of 233Pa with thenoyl trifluoroacetone. The presented method gives satisfactory accuracy and precision.

La notion de "gite epithermal uranifere" et les problemes qu'elle pose

Abstract The uraniferous veins of Limousin, France, exhibit abnormal characteristics relative to classic hydrothermal ore veins. They occur within the granulite complex of Limousin, in fractures trending roughly perpendicular to the direction of zones of high-temperature mineralization in the contact with granite masses. Genesis of the epithermal uraniferous veins is attributed to selective concentration of lithophile elements in granites which had been subjected to pneumatolytic processes; concentration was probably partly a function of material leached by ascending solutions from subjacent shattered zones.