scholarly journals Orange Pickeringite from the Algares 30-Level Adit, Aljustrel Mine, Iberian Pyrite Belt, Portugal

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1115
Author(s):  
Teresa P. Silva ◽  
João X. Matos ◽  
Daniel de Oliveira ◽  
Igor Morais ◽  
Pedro Gonçalves ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Analytical Techniques ◽  
Iberian Pyrite Belt ◽  
Water Soluble ◽  
Partial Substitution ◽  
Dark Orange ◽  
Alteration Minerals ◽  
Orange Colour ◽  
Mineral Characterization ◽  
Chemical Formulas

The sheltered environment of the Algares +30 level adit (underground mine gallery) contributes to the preservation of secondary water-soluble minerals formed on the tunnel walls. The massive sulphide and related stockwork zone are hosted by the Mine Tuff volcanic unit and are exposed in the walls of the gallery, showing intense oxidation and hydrothermal alteration. Minerals from the halotrichite group were identified on the efflorescent salts, typically white fine-acicular crystals but also on aggregates with dark orange/brownish colour. Mineral characterization was performed using several methods and analytical techniques (XRD, XRF-WDS, SEM-EDS, DTA-TG), and the chemical formulas were calculated maintaining the ratio A:B ≅ 1:2 in accordance with the general formula of the halotrichite group, AB2(SO4)4·22H2O. This methodology allowed the assignment of the orange colour to the presence of trivalent iron on iron-rich pickeringite in partial substitution of aluminium.

scholarly journals Multidimensional Analytical Characterization of Water-Soluble Organic Aerosols: Challenges and New Perspectives

2021 ◽  
Vol 11 (6) ◽  
pp. 2539
Author(s):  
Regina M. B. O. Duarte ◽  
João T. V. Matos ◽  
Armando C. Duarte
Keyword(s):  
High Resolution ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosols ◽  
Analytical Techniques ◽  
Water Soluble ◽  
Chemical Complexity ◽  
Molecular Features ◽  
High Resolution Mass ◽  
Analytical Strategies ◽  
Resolution Mass

Water-soluble organic aerosols (OA) are an important component of air particles and one of the key drivers that impact both climate and human health. Understanding the processes involving water-soluble OA depends on how well the chemical composition of this aerosol component is decoded. Yet, obtaining detailed information faces several challenges, including water-soluble OA collection, extraction, and chemical complexity. This review highlights the multidimensional non-targeted analytical strategies that have been developed and employed for providing new insights into the structural and molecular features of water-soluble organic components present in air particles. First, the most prominent high-resolution mass spectrometric methods for near real-time measurements of water-soluble OA and their limitations are discussed. Afterward, a special emphasis is given to the degree of compositional information provided by offline multidimensional analytical techniques, namely excitation–emission (EEM) fluorescence spectroscopy, high-resolution mass spectrometry and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and their hyphenation with chromatographic systems. The major challenges ahead on the application of these multidimensional analytical strategies for OA research are also addressed so that they can be used advantageously in future studies.

scholarly journals Mineral Inventory of the Algares 30-Level Adit, Aljustrel Mine, Iberian Pyrite Belt, Portugal

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 853
Author(s):  
Teresa P. Silva ◽  
João X. Matos ◽  
Daniel De Oliveira ◽  
João P. Veiga ◽  
Igor Morais ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Iberian Pyrite Belt ◽  
Mining Activity ◽  
Massive Sulphide ◽  
Principal Characteristics ◽  
Secondary Minerals ◽  
Crystalline Aggregates

Mining activity in Algares (Aljustrel Mine, Portuguese sector of the Iberian Pyrite Belt, IPB) stems prior to Roman times. As the orebody is vertical and relatively thin, mining was carried out mainly along underground adits (galleries). Nowadays, the deposit is considered exhausted and the area is being rehabilitated for a different use. The Algares +30 level adit intersects two volcanic units of the IPB Volcano-Sedimentary Complex. The massive sulphide and related stockwork zone are hosted by the Mine Tuff volcanic unit and are exposed in the walls of the gallery, showing intense hydrothermal alteration. Along the mine adit, the geological sequence is affected by strong oxidation and supergene alteration, giving rise to the formation of secondary minerals through the oxidation of the sulphides. The most common minerals found were melanterite (FeSO4·7H2O) and chalcanthite (CuSO4·5H2O), forming essentially massive or crystalline aggregates, ranging from greenish to bluish colours. Melanterite from the walls revealed to be Cu-rich by opposition to that from stalactites/stalagmites formed below the old ore storage silo revealing the low-copper-grade ores exploited underground. The mineralogy of the efflorescent salts was used to ascertain the processes involved in their formation, and moreover, the inventory of minerals is presented, as well as their principal characteristics.

Lithium-Bearing Hydrothermal Alteration Phyllosilicates Related to Portalet Fluorite Ore (Pyrenees, Huesca, Spain)

Clay Minerals ◽  
1993 ◽  
Vol 28 (2) ◽  
pp. 275-283 ◽  
Author(s):  
J. M. Gonzlez Lopez ◽  
I. Subias Pirez ◽  
C. Fernandez-Nieto ◽  
I. Fanlo Gonzalez
Keyword(s):  
Hydrothermal Alteration ◽  
Half Cell ◽  
Ore Bodies ◽  
Alteration Minerals ◽  
Structural Formulae

AbstractPhyllosilicate associations in hydrothermally altered fluorite ore bodies are: Li-chlorite ± pyrophyllite ± interstratified minerals ± muscovite +± kaolinite. Chlorites, the main alteration minerals, are dioctahedral, d060 = 1.489-1-490/~,, of Ia polytype. The structural formulae indicate substitution of AI for Si from 0.61-0.78 atoms. The total octahedral occupancy ranges from 4.52-4-71 atoms, with 0.49-0-69 Li atoms per half cell unit. This composition indicates that the chlorites are intermediate members of the donbassite-cookeite series proposed by Sudo (1978). The mineralogical associations and textural relations suggest that after intensive silicification which produced alkali alteration under acid conditions, pyrophyllite was produced at the expense of muscovite and then Li-bearing donbassite formed from the pyrophyllite. The Li needed for the formation of the chlorites could be genetically related to granitic batholiths which occur close to the fluorite ores.

Inorganic-Organic Hybrid Hierarchically Structured Methyl-modified Silica Monoliths

2004 ◽  
Vol 847 ◽  
Author(s):  
Doris Brandhuber ◽  
Nicola Hüsing ◽  
Herwig Peterlik
Keyword(s):  
Liquid Crystalline ◽  
Sol Gel ◽  
Analytical Techniques ◽  
Structural Features ◽  
Water Soluble ◽  
X Ray ◽  
Silica Monoliths ◽  
Organic Hybrid ◽  
X Ray Scattering ◽  
Highly Porous

ABSTRACTHighly porous inorganic-organic hybrid monoliths with mesopores in a macroporous network have been prepared from methyltris(2-hydroxyethoxy)silane (MeGMS) and tetrakis(2-hydroxyethoxy)silane (EGMS) in the presence of an amphiphilic block copolymer. The amount of methyltris(2-hydroxyethoxy)silane (MeGMS) in the gel has been varied from 0 to 100 %. These glycol-modified silanes have the advantage of being water-soluble and thus allowing for a direct templating of liquid-crystalline surfactant mesophases without the presence of a homogenizing organic solvent such as ethanol. The wet gels have been dried by supercritical extraction with carbon dioxide.In the present work, the sol-gel behaviour of these glycol-modified silanes is discussed especially with a focus on the formation of the meso- and macrostructure. In addition, the influences of the varying ratios of methyltris(2-hydroxyethoxy)silane on the structural features of the gels are investigated by various analytical techniques such as small angle X-ray scattering, nitrogen sorption, and scanning electron microscopy.

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