Infrared and Raman spectroscopic characterization of the arsenate mineral ceruleite Cu2Al7(AsO4)4(OH)13 11.5(H2O).

The molecular structure of the arsenate mineral ceruleite has been assessed using a combination of Raman and infrared spectroscopy. The most intense band observed at 903 cm^-1 is assigned to the (AsO4)^3- symmetric stretching vibrational mode. The infrared spectrum shows intense bands at 787, 827 and 886 cm^-1, ascribed to the triply degenerate m3 antisymmetric stretching vibration. Raman bands observed at 373, 400, 417 and 430 cm^-1 are attributed to the m2 vibrational mode. Three broad bands for ceruleite found at 3056, 3198 and 3384 cm^-1 are assigned to water OH stretching bands. By using a Libowitzky empirical equation, hydrogen bond distances of 2.65 and 2.75 Å are calculated. Vibrational spectra enable the molecular structure of the ceruleite mineral to be determined and whilst similarities exist in the spectral patterns with the roselite mineral group, sufficient differences exist to be able to determine the identification of the minerals

Ore-waste and ore type classification using portable XRF: a case study of an iron mine from the Quadrilátero Ferrífero, Brazil

Grade control is a fundamental activity for Short-Term Mine Planning as it validates the ore-waste and ore type classification of mine faces. Geological mapping and quasi-mining sampling provide indispensable information for the Short-Term Mine Planning team to update block models and for grade control of the run-of-mine (ROM). However, laboratory turnaround can take too long and not be timely for operational needs, affecting mining efficiency. To propose a solution for this issue we tested the accuracy of portable X-Ray Fluorescence (XRF) for ore-waste and ore type classification according to iron and phosphorus grade. Thus, iron ore run-of-mine samples from the Quadrilátero Ferrífero were analyzed with the portable XRF as pressed pellets. As a result, the overall accuracy of ore-waste classification was above 92% for different cut-off grades. On the other hand, while ore type classification had a better accuracy without calibration factors for iron, the use of calibration factors significantly improved the accuracy of ore type classification for phosphorus. Therefore, despite the portable XRF presenting good accuracy for ore-waste and ore type classification, further developments are still necessary on automatic information processing systems and sample support validation so that this analytical tool can be used on a large scale by grade control teams. Finally, the combined use of portable XRF and other techniques, such as Hyperspectral Sensing or XRD, can be of great value for mine operations.O controle de qualidade é uma atividade fundamental para o Planejamento de Lavra de Curto Prazo, pois valida a classificação de minério-estéril e tipo de minério nas frentes de lavra. O mapeamento geológico e a amostragem de grande volume fornecem informações indispensáveis para a equipe de Planejamento de Mina de Curto Prazo atualizar os modelos de blocos e fazer o controle de qualidade do run-of-mine. No entanto, a resposta do laboratório pode levar muito tempo e não ser oportuna para as necessidades operacionais, afetando a eficiência da mineração. Para propor uma solução para esse problema, testamos a acurácia da espectrometria por Fluorescência de Raios X (FRX) portátil para classificação de minério-estéril e tipos de minério de acordo com o teor de ferro e fósforo. Assim, amostras de minério de ferro do Quadrilátero Ferrífero foram analisadas pela FRX portátil como pastilhas prensadas. Como resultado, a acurácia geral da classificação de minério-estéril foi superior a 92% para diferentes teores de corte. Por outro lado, enquanto a classificação dos diferentes tipos de minério teve uma melhor acurácia sem fatores de calibração para o ferro, o uso destes fatores melhorou significativamente a acurácia da classificação do tipo de minério em relação ao fósforo. Portanto, apesar da FRX portátil apresentar boa acurácia para o controle de qualidade, ainda são necessários mais avanços em relação a sistemas automatizados de processamento de informações e validação do suporte amostral para que esta ferramenta possa ser usada em larga escala pelas equipes de controle de qualidade. Finalmente, o uso combinado da FRX portátil e outras técnicas, como análise por Imagens Hiperespectrais ou Difratometria de Raios-X (DRX), pode ser de

A vibrational spectroscopic study of the copper bearing silicate mineral luddenite.

The molecular structure of the copper?lead silicate mineral luddenite has been analysed using vibrational spectroscopy. The mineral is only one of many silicate minerals containing copper. The intense Raman band at 978 cm 1 is assigned to the m1 (A1g) symmetric stretching vibration of Si5O14 units. Raman bands at 1122, 1148 and 1160 cm 1 are attributed to the m3 SiO4 antisymmetric stretching vibrations. The bands in the 678?799 cm 1 are assigned to OSiO bending modes of the (SiO3)n chains. Raman bands at 3317 and 3329 cm 1 are attributed to water stretching bands. Bands at 3595 and 3629 cm 1 are associated with the stretching vibrations of hydroxyl units suggesting that hydroxyl units exist in the structure of luddenite

Raman spectroscopy of the arsenate minerals maxwellite and in comparison with tilasite.

Maxwellite NaFe3+(AsO4)F is an arsenate mineral containing fluoride and forms a continuous series with tilasite CaMg(AsO4)F. Both maxwellite and tilasite form a continuous series with durangite NaAl3+(AsO4)- F. We have used the combination of scanning electron microscopy with EDS and vibrational spectroscopy to chemically analyse the mineral maxwellite and make an assessment of the molecular structure. Chemical analysis shows that maxwellite is composed of Fe, Na and Ca with minor amounts of Mn and Al. Raman bands for tilasite at 851 and 831 cm_1 are assigned to the Raman active m1 symmetric stretching vibration (A1) and the Raman active triply degenerate m3 antisymmetric stretching vibration (F2). The Raman band of maxwellite at 871 cm_1 is assigned to the m1 symmetric stretching vibration and the Raman band at 812 cm_1 is assigned to the m3 antisymmetric stretching vibration. The intense Raman band of tilasite at 467 cm_1 is assigned to the Raman active triply degenerate m4 bending vibration (F2). Raman band at 331 cm_1 for tilasite is assigned to the Raman active doubly degenerate m2 symmetric bending vibration (E). Both Raman and infrared spectroscopy do not identify any bands in the hydroxyl stretching region as is expected

The molecular structure of the borate mineral szaibelyite MgBO2(OH) : a vibrational spectroscopic study.

We have studied the borate mineral szaibelyite MgBO2(OH) using electron microscopy and vibrational spectroscopy. EDS spectra show a phase composed of Mg with minor amounts of Fe. Both tetrahedral and trigonal boron units are observed. The nominal resolution of the Raman spectrometer is of the order of 2 cm 1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. The Raman band at 1099 cm 1 with a shoulder band at 1093 cm 1 is assigned to BO stretching vibration. Raman bands at 1144, 1157, 1229, 1318 cm 1 are attributed to the BOH in-plane bending modes. Raman bands at 836 and 988 cm 1 are attributed to the antisymmetric stretching modes of tetrahedral boron. The infrared bands at 3559 and 3547 cm 1 are assigned to hydroxyl stretching vibrations. Broad infrared bands at 3269 and 3398 cm 1 are assigned to water stretching vibrations. Infrared bands at 1306, 1352, 1391, 1437 cm 1 are assigned to the antisymmetric stretching vibrations of trigonal boron. Vibrational spectroscopy enables aspects of the molecular structure of the borate mineral szaibelyite to be assessed

The molecular structure of the phosphate mineral senegalite Al2(PO4)(OH)3-3H2O - a vibrational spectroscopic study.

We have studied the mineral senagalite, a hydrated hydroxy phosphate of aluminium with formula Al2(-PO4)(OH)3_3H2O using a combination of electron microscopy and vibrational spectroscopy. Senegalite crystal aggregates shows tabular to prismatic habitus and orthorhombic form. The Raman spectrum is dominated by an intense band at 1029 cm_1 assigned to the PO3_ 4 m1 symmetric stretching mode. Intense Raman bands are found at 1071 and 1154 cm_1 with bands of lesser intensity at 1110, 1179 and 1206 cm_1 and are attributed to the PO3_ 4 m3 antisymmetric stretching vibrations. The infrared spectrum shows complexity with a series overlapping bands. A comparison is made with spectra of other aluminium containing phosphate minerals such as augelite and turquoise. Multiple bands are observed for the phosphate bending modes giving support for the reduction of symmetry of the phosphate anion. Vibrational spectroscopy offers a means for the assessment of the structure of senagalite

Formation conditions and 40Ar/39Ar age of the Gem-Bearing Boqueir?o Granitic Pegmatite, Parelhas, Rio Grande do Norte, Brazil.

The Boqueir?o granitic pegmatite, alias Alto da Cabe?a pegmatite, is situated in Borborema Pegmatitic Province (BPP) in Northeast Brazil. This pegmatitic province hosts globally important reserves of tantalum and beryllium, as well as significant quantities of gemstones, including aquamarine, morganite, and the high-quality turquoise-blue ?Para?ba Elbaite?. The studied lithium-cesium-tantalum Boqueir?o granitic pegmatite intruded meta-conglomerates of the Equador Formation during the late Cambrian (502.1 ? 5.8 Ma; 40Ar/39Ar plateau age of muscovite). The pegmatite exhibits a typical zonal mineral pattern with four defined zones (Zone I: muscovite, tourmaline, albite, and quartz; Zone II: K-feldspar (microcline), quartz, and albite; Zone III: perthite crystals (blocky feldspar zone); Zone IV: massive quartz). Huge individual beryl, spodumene, tantalite, and cassiterite crystals are common as well. Microscopic examinations revealed that melt inclusions were entrapped simultaneously with fluid inclusions, suggesting the magmatic?hydrothermal transition. The magmatic?hydrothermal transition affected the evolution of the pegmatite, segregating volatile compounds (H2O, CO2, N2) and elements that preferentially partition into a fluid phase from the viscous silicate melt. Fluid inclusion studies on microcline and associated quartz combined with microthermometry and Raman spectroscopy gave an insight into the P-T-X characteristics of entrapped fluids. The presence of spodumene without other LiAl(SiO3)2 polymorphs and constructed fluid inclusion isochores limited the magmatic?hydrothermal transition at the gem-bearing Boqueir?o granitic pegmatite to the temperature range between 300 and 415 ?C at a pressure from 1.8 to 3 kbar. View Full-Tex

A vibrational spectroscopic study of the silicate mineral harmotome ? (Ba,Na,K)1-2(Si,Al)8O16 6H2O ? a natural zeolite.

The mineral harmotome (Ba,Na,K)1-2(Si,Al)8O16 6H2O is a crystalline sodium calcium silicate which has the potential to be used in plaster boards and other industrial applications. It is a natural zeolite with catalytic potential. Raman bands at 1020 and 1102 cm 1 are assigned to the SiO stretching vibrations of three dimensional siloxane units. Raman bands at 428, 470 and 491 cm 1 are assigned to OSiO bending modes. The broad Raman bands at around 699, 728, 768 cm 1 are attributed to water librational modes. Intense Raman bands in the 3100 to 3800 cm 1 spectral range are assigned to OH stretching vibrations of water in harmotome. Infrared spectra are in harmony with the Raman spectra. A sharp infrared band at 3731 cm 1 is assigned to the OH stretching vibration of SiOH units. Raman spectroscopy with complimentary infrared spectroscopy enables the characterization of the silicate mineral harmotome

The molecular structure of the borate mineral inderite Mg(H4B3O7)(OH)-5H2O - a vibrational spectroscopic study.

We have undertaken a study of the mineral inderite Mg(H4B3O7)(OH)_5H2O a hydrated hydroxy borate mineral of magnesium using scanning electron microscopy, thermogravimetry and vibrational spectroscopic techniques. The structure consists of ?B3O3?OH?5_2_ soroborate groups and Mg(OH)2(H2O)4 octahedra interconnected into discrete molecules by the sharing of two OH groups. Thermogravimetry shows a mass loss of 47.2% at 137.5 _C, proving the mineral is thermally unstable. Raman bands at 954, 1047 and 1116 cm_1 are assigned to the trigonal symmetric stretching mode. The two bands at 880 and 916 cm_1 are attributed to the symmetric stretching mode of the tetrahedral boron. Both the Raman and infrared spectra of inderite show complexity. Raman bands are observed at 3052, 3233, 3330, 3392 attributed to water stretching vibrations and 3459 cm_1 with sharper bands at 3459, 3530 and 3562 cm_1 assigned to OH stretching vibrations. Vibrational spectroscopy is used to assess the molecular structure of inderite

Estudo dos fosfatos do distrito pegmatítico de Conselheiro Pena, Minas Gerais

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Nestes corpos destaca-se um grande número de fosfatos raros, incluindo a primeira descrição de espécimes minerais, como a brazilianita, a scorzalita e a souzalita do pegmatito Córrego Frio em Divino das Laranjeiras, a moraesita, a barbosalita, a faheyita, afrondelita, a lipscombita e a tavorita do pegmatito Sapucaia, no município de Galiléia. A maior parte dos pegmatitos é lavrada visando a produção de minerais industriais e principalmente de minerais gemológicos, sendo os mais importantes a turmalina, berilo, quartzo,espodumênio e, em menor quantidade, fosfatos como a brazilianita, ambligonita/montebrasita, apatita e eosforita. A mineralogia fosfática dos corpos amostrados não indica haver relação entre o enriquecimento em minerais fosfatos e o grau de fracionamento dos pegmatitos, entretanto, a maior parte dos pegmatitos estudados é classificada como ricos em elementos raros. Treze corpos amostrados foram subdivididos em cinco tipos, com base na mineralogia fosfática primária, ou na ausência desta.Foram identificadas diversas paragêneses minerais, algumas destas são compostas por fosfatos primários e incluem, também, minerais secundários como produto de alteração hidrotermal e/ou supergênica.O estudo sistemático de minerais da série childrenita-eosforita e da ernstita indicou a presença de Fe(III) na estrutura destes minerais ocupando o sitio octahédrico do Al(III).The mining in pegmatites of the Conselheiro Pena Pegmatitic District is responsible for theproduction of an important amount of production of gemstones and collectors minerals. The rarephosphate minerals are commonplace in the pegmatite bodies in this District. Minerals such asbrazilianite, scorzalite and souzalite were discovered in the Córrego Frio Pegmatite, Divino dasLaranjeiras region, and the moraesite, barbosalite, faheite, frondelite, lipscombite and tavorite werediscovered in the Sapucaia Pegmatite, Galiléia region.The pegmatites are mined for industrial minerals and gemstones. The most importantsgemological minerals are the tourmaline, beryl, quartz, kunzite, hiddenite and in less quantityphosphatic minerals such as brazilianite, amblygonite/montebrasite, apatite and eosphorite.The phosphatic mineralogy found in the pegmatite bodies don´t show any relation betweenthe enrichment in phosphate minerals and degree of diferenciation of pegmatites. Twentypegmatites were sampled and divided in 5 types, using the primary phosphatic mineralogy, or theabsence of phosphatic primary phases.Several phosphatic paragenesis were found, and some of this are composed by primaryphosphates and their alteration products. Some secondaries phosphates occur such as hydrotermalor supergenic alteration.The systematic study of childrenite-eosphorite and ernstite show the presence of Fe(III) in theoctahedric site of Al(III)