1,721,059 research outputs found
Where Do LCT and NYF Pegmatites Fit In? A Contribution to a Revised Classification of Granitic Pegmatites
No full textOral presentation
Communicating author: RF Marti
Benefits of a Classification Scheme of Granitic Pegmatites Based on Petrogenetic Considerations.
No full textOral presentation-
Communicating author: Martin RF
WHY IS AMAZONITIC K-FELDSPAR AN EARMARK OF NYF-TYPE GRANITIC PEGMATITES?
No full textOral presentation- Communicating author: Martin R
Minerali di Nb e Ta nelle pegmatiti dell’isola d’Elba, di Baveno e della Val d’Ossola: caratterizzazione geochimica e cristallochimica.
No full textDegree thesis,Department of Earth Sciences University “ La Sapienza”, Rome Italy
Il giacimento gemmifero e ad elementi rari dell'Anjanabonoina, Betafo, Madagascar Centrale
No full textMetal analyses. Some case studies from Motya
Full text linkThe aim of this investigation is to reconstruct the archeometallurgical processes, manufacturingtechniques, and cycle-life of Motyan (Sicily, Italy) metallic artefacts from metals extraction to corrosion. The research was developed through five case studies, for which metallurgical and corrosion processes are reconstructed
Boron isotope systematics and petrologic inferences of high-evolved pegmatites of the Itremo Group, Central Madagarcar.
No full textOral presentation- Communicating author: Pezzotta F
Structural control and rheological properties of the hydrothermal mineralization:a case of a mineralized mafic dike outcropping near Lula, Sardinia, Italy
No full textOral presentation;
communicating author: De Vit
THE LATE-STAGE MINIFLOOD OF Ca IN GRANITIC PEGMATITES: AN OPEN-SYSTEM ACID-REFLUX MODEL INVOLVING PLAGIOCLASE IN THE EXOCONTACT
No full textAs Richard H. Jahns used to say, granitic pegmatites are prone to stew in their own juice. The early juice acts as a catalyst in transforming the early-formed disordered K-feldspar to microcline below 450 degrees C. As it becomes progressively enriched in fluorine during the system's evolution, the exsolved fluid becomes increasingly aggressive, and can create cavities by dissolution. It eventually leaks into the country rock, mostly from the apical parts of zoned pegmatites. There, it interacts with plagioclase in any lithology it encounters. As the plagioclase is highly strained and kinetically stuck, it is consumed, and the fluid quickly becomes more aluminous, more acidic and Ca-bearing. We envision a convecting fluid phase cycling around the pegmatite body, and a reaction path that brings the acidified fluid back into the heart of the pegmatite. There, it is aggressive toward the microcline perthite, which is replaced by cleavelanditic albite + muscovite + quartz, mostly in the range 250-400 degrees C, a process that enlarges the original cavities and creates new ones. Miarolitic pegmatites of either NYF and LCT affiliation contain clear signs of the presence of cations brought in from outside the system, mostly Ca (causing a miniflood of Ca), but also Sr, Fe, Mg, Sc, Li and F. Other elements are efficiently recycled internally. The recurrent cycling of an aqueous fluid has major ramifications concerning the economic aspects of granitic pegmatites. In particular, the cycles of hydrothermal enrichment in a large LCT pegmatite can give rise to zones enriched in micas of the lepidolite series, pollucite, tantalite-(Fe) and tantalite-(Mn), i.e., super-LCT deposits
Synthesis of nesquehonite by reaction of gaseous CO2 with Mg chloride solution: Its potential role in the sequestration of carbon dioxide
No full textIn this paper is reported a novel method to synthesize nesquehonite, MgCO3-3H(2)O, via reaction of a flux of CO2 with Mg chloride solution at 20 +/- 2 degrees C. The reaction rate is rapid, with carbonate deposition almost complete in about 10 min. The full characterization of the product of synthesis has been performed to investigate its potential role as a "CO2-sequestering medium" and a means of disposing Mg-rich wastewater. We investigated the nesquehonite synthesized using SEM, XRD, FTIR and thermal analysis. The thermodynamic and chemical stability of this low-temperature hydrated carbonate of Mg and its possible transformation products make our method a promising complementary solution to other methods of CO2 sequestration. Carbonation via magnesium chloride aqueous solutions at standard conditions represents a simple and permanent method of trapping CO2. It could be applied at point sources of CO2 emission and could involve rejected brine from desalination plants and other saline aqueous wastes (i.e., "produced water"). The likelihood of using the resulting nesquehonite and the by-products of the process in a large number of applications makes our method an even more attractive solution. (C) 2009 Elsevier B.V. All rights reserved
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