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Khalidinul Ihsan - One of the best experts on this subject based on the ideXlab platform.
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SINTESIS FOTOKATALIS KOMPOSIT TIO DARI BIJIH BESI DENGAN METODE SONIKASI DAN APLIKASINYA PADA FOTODEGRADASI ZAT WARNA INDIGO KARMIN
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM UNIVERSITAS SYIAH KUALA, 2019Co-Authors: Khalidinul IhsanAbstract:Modifikasi hematit (?-Fe2O3ABSTRAK ) dengan TiO untuk menghasilkan komposit TiO2/?-Fe2O32 melalui metode sonikasi serta uji aktivitas fotokatalitiknya padadegradasi zat warna indigo karmin telah dilakukan. Hematit diestraksi dari bijihbesi menggunakan asam klorida (HCl) dan presipitasi menggunakan ammoniumhidroksida (NHOH). Titanium (IV) dioksida yang digunakan berasal darititanium tetraisopropoksida. Fotokatalis komposit TiO42/?-Fe dipreparasidengan perbandingan mol TiO2 dan ?-Fe2O32 1:3, 3:1 dan 1:1. Karakterisasimenggunakan X-Ray Diffraction (XRD) dan Scanning Electron MicroscopyEnergyDispersiveX-Ray Spectroscopy (SEM-EDS) dilakukan untuk mengetahuisifat fisik dan kimia dari hematit dan komposit TiO2/?-Fe2O. Hasil uji aktivitasfotokatalitik menunjukkan bahwa fotokatalis komposit TiO32O3/?-Fe denganperbandingan mol TiO2 dan ?-Fe2O 1:3 memiliki aktivitas paling tinggi, denganpersen degradasi (% D) sebesar 92,70% menggunakan sinar ultra violet; 90,99%menggunakan lampu flouresen dan 94,06% menggunakan sinar matahari.Aktivitas fotokatalitik tersebut diperoleh pada kondisi pH larutan zat warna = 1,massa fotokatalis 350 mg, konsentrasi awal zat warna 20 ppm, dengan wakturadiasi 120 menit menggunakan sinar UV dan lampu flouresen serta 30 menitmenggunakan cahaya matahari. Kata kunci : Fotokatalis, Indigo karmin, ?-FeModification of Hematite (?-Fe32ABSTRACT 2O3O3 dan TiO) with TiO22/?-Fe2O3 to produce TiOcomposites by sonication method and their photocatalytic activity testing on thedegradation of indigo carmine dyes has been done. The Hematite was etractedfrom iron sand by using hydrochloric acid (HCl) and precipitation by usingammonium hydroxide (NHOH). The precursor of titanium (IV) dioxide wastitanium tetraisopropoxide. TiO42/?-Fe2Ocomposites photocatalysts wereprepared with the mole ratio of TiO2 to ?-Fe3 2O 1;3, 3;1 and 1;1. Characterizationof ?-Fe2O3 and TiO2/?-Fe2O33 composites was carried out in order to determinetheir physical and chemical properties. The result photocatalytic activities testingshowed that the TiO2/?-Fe2O3 composite with the mole ratio of TiO1;3 has the highest activity with the percent degradation (%D) of indigo carminedye was 92.70 % under ultra violet light ; 90.99 % under fluorescent lamp and94.06 % under solar light irradiation, respectively. These highest photocatalyticactivity were obtained at the initial pH of dye solution 1, the photocatalyst mass of350 mg, the initial dye concentration was 20 ppm, irradiation time 120 minutesunder UV light and fluorescent lamp and 30 minutes under solar light irradiation.Keywords : photocatalyst, indigo carmine, ?-Fe2O3 and TiO2/?-Fe2O223 O32/?-Fe to ?-Fe22OO3 3Banda Ace
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SINTESIS FOTOKATALIS KOMPOSIT TIO2/?-FE2O3 DARI BIJIH BESI DENGAN METODE SONIKASI DAN APLIKASINYA PADA FOTODEGRADASI ZAT WARNA INDIGO KARMIN
'Fakultas MIPA Universitas Negeri Makassar', 2019Co-Authors: Khalidinul IhsanAbstract:ABSTRAKModifikasi hematit (?-Fe2O3) dengan TiO2 untuk menghasilkan komposit TiO2/?-Fe2O3 melalui metode sonikasi serta uji aktivitas fotokatalitiknya pada degradasi zat warna indigo karmin telah dilakukan. Hematit diestraksi dari bijih besi menggunakan asam klorida (HCl) dan presipitasi menggunakan ammonium hidroksida (NH4OH). Titanium (IV) dioksida yang digunakan berasal dari titanium tetraisopropoksida. Fotokatalis komposit TiO2/?-Fe2O3 dipreparasi dengan perbandingan mol TiO2 dan ?-Fe2O3 1:3, 3:1 dan 1:1. Karakterisasi menggunakan X-Ray Diffraction (XRD) dan Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) dilakukan untuk mengetahui sifat fisik dan kimia dari hematit dan komposit TiO2/?-Fe2O3. Hasil uji aktivitas fotokatalitik menunjukkan bahwa fotokatalis komposit TiO2/?-Fe2O3 dengan perbandingan mol TiO2 dan ?-Fe2O3 1:3 memiliki aktivitas paling tinggi, dengan persen degradasi (% D) sebesar 92,70% menggunakan sinar ultra violet; 90,99% menggunakan lampu flouresen dan 94,06% menggunakan sinar matahari. Aktivitas fotokatalitik tersebut diperoleh pada kondisi pH larutan zat warna = 1, massa fotokatalis 350 mg, konsentrasi awal zat warna 20 ppm, dengan waktu radiasi 120 menit menggunakan sinar UV dan lampu flouresen serta 30 menit menggunakan cahaya matahari. Kata kunci : Fotokatalis, Indigo karmin, ?-Fe2O3 dan TiO2/?-Fe2O3ABSTRACTModification of Hematite (?-Fe2O3) with TiO2 to produce TiO2/?-Fe2O3 composites by sonication method and their photocatalytic activity testing on the degradation of indigo carmine dyes has been done. The Hematite was etracted from iron sand by using hydrochloric acid (HCl) and precipitation by using ammonium hydroxide (NH4OH). The precursor of titanium (IV) dioxide was titanium tetraisopropoxide. TiO2/?-Fe2O3 composites photocatalysts were prepared with the mole ratio of TiO2 to ?-Fe2O3 1;3, 3;1 and 1;1. Characterization of ?-Fe2O3 and TiO2/?-Fe2O3 composites was carried out in order to determine their physical and chemical properties. The result photocatalytic activities testing showed that the TiO2/?-Fe2O3 composite with the mole ratio of TiO2 to ?-Fe2O3 1;3 has the highest activity with the percent degradation (%D) of indigo carmine dye was 92.70 % under ultra violet light ; 90.99 % under fluorescent lamp and 94.06 % under solar light irradiation, respectively. These highest photocatalytic activity were obtained at the initial pH of dye solution 1, the photocatalyst mass of 350 mg, the initial dye concentration was 20 ppm, irradiation time 120 minutes under UV light and fluorescent lamp and 30 minutes under solar light irradiation. Keywords : photocatalyst, indigo carmine, ?-Fe2O3 and TiO2/?-Fe2O3Banda Ace
Leonardo Evangelista Lagoeiro - One of the best experts on this subject based on the ideXlab platform.
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crystallographic texture of the magnetite Hematite transformation evidence for topotactic relationships in natural samples from quadrilatero ferrifero brazil
American Mineralogist, 2010Co-Authors: Paola Barbosa, Leonardo Evangelista LagoeiroAbstract:The transformation of magnetite to Hematite is described and analyzed in three natural samples of banded iron formation, from Quadrilatero Ferrifero, Brazil. In each sample, a particular microstructure related to the transformation process is described. In the first, magnetite crystals are large and euhedral, and they display the beginning of the transformation into Hematite. In the second sample, a relict crystal of magnetite was found and the fabric of the transformed Hematite was evaluated. In the last sample, the foliation was the main observed structure and the correlations of magnetite and Hematite lattices were measured. All the microstructures were analyzed in a scanning electron microscope equipped with a detector for electron backscatter diffraction allowing the complete analysis of crystallographic orientations of Hematite and magnetite on a local scale. The results show that the orientations of the basal planes of Hematite coincide with the orientations of the octahedral planes of magnetite, indicating that the Hematite crystals are a direct product from the magnetite transformation.
Fakhruddin, Miftahul Jannah - One of the best experts on this subject based on the ideXlab platform.
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Sintesis pigmen hematit (α-Fe2O3) dari limbah bubut besi dengan variasi waktu sonikasi dan aplikasinya sebagai anti swelling pada kayu
2019Co-Authors: Fakhruddin, Miftahul JannahAbstract:INDONESIA: Limbah bubut besi merupakan limbah yang berasal dari industri kerajinan besi yang dalam bentuk serbuknya langsung dibuang ke lingkungan dan termasuk limbah bahan berbahaya dan beracun (B3) yang dapat berpotensi mencemari lingkungan. Limbah ini mengandung besi (Fe) yang cukup besar, sehingga dapat dimanfaatkan sebagai bahan baku (prekursor) untuk mensintesis pigmen besi oksida. Pada penelitian ini dilakukan sintesis pigmen hematit (α-Fe2O3) dengan metode rute presipitasi-sonikasi dan dengan variasi waktu sonikasi 30, 45 dan 60 menit. Proses presipitasi menggunakan agen pengendap urea dan proses kalsinasi selama 3 jam pada suhu 750oC. Prekursor dikarakterisasi menggunakan XRF sedangkan hasil sintesis dikarakterisasi menggunakan teknik difraksi sinar-X (XRD), color reader dan hasil terbaik dikarakterisasi dengan SEM-EDX. Pigmen hematit (α-Fe2O3) yang dihasilkan kemudian diaplikasikan terhadap kayu untuk menguji daya swelling pada kayu. Data XRD menunjukkan bahwa pada semua variasi sintesis yang dilakukan berhasil diperoleh fasa hematit dan sampel dengan waktu sonikasi 60 menit mempunyai derajat kristalinitas yang paling tinggi. Gambar SEM menunjukkan bahwa semakin lama waktu sonikasi morfologi α-Fe2O3 semakin seragam dengan tingkat aglomerasi yang berkurang dan hasil EDX ditemukan pengotor berupa unsur C. Data hasil colour reader yang menunjukkan nilai warna L*, a*, b*, C* dan Ho pada semua pigmen hasil sintesis sesuai dengan standar hematit. Hasil aplikasi pigmen pada kayu menunjukkan bahwa pigmen hematit hasil sintesis dapat mengurangi daya swelling pada kayu. Pigmen dengan variasi waktu 30;45; dan 60 menit pada hari ke-7 menghasilkan % ASE berturut-turut 80,99; 78,02; dan 66,24%. ENGLISH: Lathe waste is waste generated from the iron craft industry which in the form of powder is directly discharged into the environment and includes hazardous and diverted (B3) waste that can be used to pollute the environment. This waste contains iron (Fe) which is large enough, so that it can be used as a raw material (precursor) to synthesize iron oxide pigments. In this research, synthesis of Hematite pigment (α-Fe2O3) was carried out by the precipitation-sonication route method and with variations in sonication time of 30, 45 and 60 minutes. The precipitation process uses urea precipitating agents and calcination process for 3 hours with 750°C temperature. The precursors were characterized using XRF while the synthesis results were characterized using X-ray diffraction (XRD) techniques, color reader and the best results were characterized by SEM-EDX. Hematite pigment (α-Fe2O3) produced then applied to wood to test the swelling power of the wood. The XRD data showed that in all variations of synthesis performed successfully obtained Hematite phase and at sonication time of 60 minutes the synthesized sample has the highest degree of crystallinity. SEM pictures show that the longer the sonication time of morphology α-Fe2O3 the more uniform with the reduced agglomeration level and the EDX results found impurities in the form of element C. Data from the color reader that shows the color values of L*, a*, b*, C* and Ho in all pigments resulting from the synthesis are in accordance with Hematite standards. The results of the application of pigments in wood showed that synthesized Hematite pigments can reduce swelling power in wood. Pigment with time variation of 30; 45; and 60 minutes on day 7 produce %ASE is 80,99; 78,02; and 66,24%
Juliano Volpato - One of the best experts on this subject based on the ideXlab platform.
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Relation between geochemistry and minerals (Magnetite, Hematite, Pyrite, and Vivianite) in contaminated estuarine sediments, Santos, São Paulo, Brazil
2017Co-Authors: Juliano VolpatoAbstract:Resumo: A existência de sedimentos altamente enriquecidos principalmente por Fe e P, provenientes das indústrias siderúrgica e de fertilizantes localizadas próximas ao estuário do rio Morrão, um dos principais receptores de efluentes industriais do Sistema Estuarino de Santos-Cubatão (São Paulo Brasil), juntamente com as condições físico-químicos do meio, constitui elementos especiais para avaliar se as condições formadoras de minerais como magnetita, hematita, pirita e vivianita podem ser influenciadas por contribuições químicas antrópicas. Este trabalho analisou as condições de formação desses minerais nos sedimentos superficiais do estuário do rio Morrão, na sua relação com a geoquímica dos sedimentos, condições físico-químicas, texturas sedimentares e conteúdo de matéria orgânica. A coleta de sedimentos de superfície consistiu em uma malha amostral de 10 x 10 m, em três transectos paralelos que cruzaram perpendicularmente o canal do rio Morrão. Os resultados mostraram que os sedimentos do rio Morrão encontram-se enriquecidos em diversos elementos químicos dentre os quais Fe, P, elementos terras raras (ETR) e vários metais-traço. O ambiente sedimentar do rio Morrão mostrou-se favorável à autigênese e coexistência de minerais como hematita, magnetita, pirita e vivianita. As fases minerais hematita e magnetita ocorrem amplamente no ambiente, já as fases minerais pirita e vivianita têm sua distribuição mais restrita. Os locais mais favoráveis à ocorrência de pirita e vivianita foram áreas de menor energia de fluxo, tais como planícies de intermaré lamosa, onde há altos teores de enxofre, ferro, fósforo, matéria orgânica e sedimentos finos.Abstract: The presence of sediments highly enriched by contaminant elements, mainly Fe and P, derived from a steel plant and fertilizer industries located near the Morrão River Estuary, the most anthropogenically influenced estuary of the Santos-Cubatão Estuarine System (São Paulo, Brazil), together with the environment physic-chemical conditions constitute special elements to evaluate if the forming conditions of mineral such as magnetite, Hematite, pyrite and vivianite can be influenced by the anthropogenic input into the environment. This work studied the forming conditions of these minerals in the superficial sediments of the Morrão River Estuary in its relation with sediment geochemistry, physicochemical conditions, sedimentary texture, and organic matter content. The sample collection comprised a 10 by 10 meters grid composed of three parallel transects crossing perpendicularly the Morrão River channel. The results showed the sediments of Morrão River Estuary are enriched by several chemical elements among which Fe, P, REE and multiple trace elements. The sedimentary environment of the Morrão River showed to be propitious to the authigenesis and coexistence minerals such as Hematite, magnetite, pyrite, and vivianite. Magnetite and Hematite broadly occur in the environment, and pyrite and vivianite have restrict distribution. Moreover, the places more favorable to the pyrite and vivianite occurrence are areas with low water flux action, such as the intertidal mudflats, where concentrations of S, Fe, P, organic matter, and fine sediments are high
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Relation between geochemistry and minerals (Magnetite, Hematite, Pyrite, and Vivianite) in contaminated estuarine sediments, Santos, São Paulo, Brazil
Universidade Estadual de Campinas. Instituto de Geociências, 2015Co-Authors: Juliano VolpatoAbstract:A existência de sedimentos altamente enriquecidos principalmente por Fe e P, provenientes das indústrias siderúrgica e de fertilizantes localizadas próximas ao estuário do rio Morrão, um dos principais receptores de efluentes industriais do Sistema Estuarino de Santos-Cubatão (São Paulo Brasil), juntamente com as condições físico-químicos do meio, constitui elementos especiais para avaliar se as condições formadoras de minerais como magnetita, hematita, pirita e vivianita podem ser influenciadas por contribuições químicas antrópicas. Este trabalho analisou as condições de formação desses minerais nos sedimentos superficiais do estuário do rio Morrão, na sua relação com a geoquímica dos sedimentos, condições físico-químicas, texturas sedimentares e conteúdo de matéria orgânica. A coleta de sedimentos de superfície consistiu em uma malha amostral de 10 x 10 m, em três transectos paralelos que cruzaram perpendicularmente o canal do rio Morrão. Os resultados mostraram que os sedimentos do rio Morrão encontram-se enriquecidos em diversos elementos químicos dentre os quais Fe, P, elementos terras raras (ETR) e vários metais-traço. O ambiente sedimentar do rio Morrão mostrou-se favorável à autigênese e coexistência de minerais como hematita, magnetita, pirita e vivianita. As fases minerais hematita e magnetita ocorrem amplamente no ambiente, já as fases minerais pirita e vivianita têm sua distribuição mais restrita. Os locais mais favoráveis à ocorrência de pirita e vivianita foram áreas de menor energia de fluxo, tais como planícies de intermaré lamosa, onde há altos teores de enxofre, ferro, fósforo, matéria orgânica e sedimentos finos.The presence of sediments highly enriched by contaminant elements, mainly Fe and P, derived from a steel plant and fertilizer industries located near the Morrão River Estuary, the most anthropogenically influenced estuary of the Santos-Cubatão Estuarine System (São Paulo, Brazil), together with the environment physic-chemical conditions constitute special elements to evaluate if the forming conditions of mineral such as magnetite, Hematite, pyrite and vivianite can be influenced by the anthropogenic input into the environment. This work studied the forming conditions of these minerals in the superficial sediments of the Morrão River Estuary in its relation with sediment geochemistry, physicochemical conditions, sedimentary texture, and organic matter content. The sample collection comprised a 10 by 10 meters grid composed of three parallel transects crossing perpendicularly the Morrão River channel. The results showed the sediments of Morrão River Estuary are enriched by several chemical elements among which Fe, P, REE and multiple trace elements. The sedimentary environment of the Morrão River showed to be propitious to the authigenesis and coexistence minerals such as Hematite, magnetite, pyrite, and vivianite. Magnetite and Hematite broadly occur in the environment, and pyrite and vivianite have restrict distribution. Moreover, the places more favorable to the pyrite and vivianite occurrence are areas with low water flux action, such as the intertidal mudflats, where concentrations of S, Fe, P, organic matter, and fine sediments are high
Cabral, Alexandre Raphael - One of the best experts on this subject based on the ideXlab platform.
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Mineralização de ouro paladiado em itobiritos : a jacutinga de Gongo Soco, Quadrilatero Ferrifero, Minas Gerais
[s.n.], 2018Co-Authors: Cabral, Alexandre RaphaelAbstract:Orientadores: Roberto Perez Xavier, Fernando Roberto Mendes PiresDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de GeocienciasResumo: A mina de Gongo Soco tomou-se célebre por volta de 1830 pelo seu minério aurífero de alto teor. Em 30 anos (1826-1856) a companhia inglesa Imperial Brazilian Mining Association produziu 12.887 kg de ouro. Apesar da importância econômica e histórica da mina de Gongo Soco, a gênese de seu minério é ainda pouco conhecida devido, em parte, à inacessibilidade aos antigos trabalhos mineiros subterrâneos. O presente estudo tem contemplado os corpos auríferos recentemente expostos pela lavra de minério de ferro na mina de ferro de Gongo Soco. O empreendimento inglês lavrou estreitos leitos auríferos entremeados concordantemente ao minério de ferro brando de alto teor da formação ferrífera Itabira (FFl), paleoproterozóica, do Quadrilátero Ferrífero (QF), Minas Gerais, Brasil. Os corpos auríferos, conhecidos como jacutinga, eram compostos de hematita especular, talco, caulinita e óxido de manganês, e caracterizava-se pela ausência de minerais sulfurados. A disposição linear dos corpos de minério na direção leste é atribuído à lineação de estiramento com caimento para leste. O ouro tipicamente ocorre como partículas livres ou como inclusões em hematita especular, pirolusita ou goethita. Dois estágios de mineralização aurífera hidrotermal são propostos: (i) um estágio inicial sincrônico à formação da hematita especular e talco e (ü) uma deposição em baixa temperatura, com goethita e pirolusita. Atribui-se a processos supergênicos o enriquecimento final em ouro. A morfologia dos grãos de ouro varia desde formas prolatas e encurvadas àquelas arredondadas e facetadas. Análises por microssonda eletrônica de grãos de ouro têm confirmado existência de paládio, ainda que em quantidades menores que aquelas reportadas na literatura do século XIX. A prata excede o conteúdo de paládio em até cinco vezes. Uma intrigante película negra de paládio e ferro ao redor de grão de ouro é digno de menção. Um ambiente hidrotermal oxidante e ácido é assumido com base na existência de hematita especular e caulinita. Nestas condições (tampão hematita-magnetita) espera-se que o ouro seja transportado como complexos clorados. Um mecanismo de deposição eficiente se processa quando tal fluido reage com magnetita e promove sua oxidação para hematita, precipitando ouro de sua forma aquosa. A interface entre a capa de hematita dura impermeável e a lapa de itabirito silicoso seria um sítio adequado à passagem de fluido e à reações de precipitação. Este cenário coincide com o metamorfismo ácido e oxidante da FFI em sua zona da cummingtonita. A medida que a temperatura decresce, a fugacidade de oxigênio aumenta suficientemente para precipitar óxido/hidróxido de manganês e goethita juntamente com ouro. Este estágio tardio de mineralização aurífera, em que o ouro é solúvel como complexo clorado, é considerada uma remobilização do estágio inicial, de temperatura mais elevada. Alguns dados de homogeneização de inclusões fluidas em tomo de 130°C estão compatíveis com a assembléia goethita-pirolusita; salinidades variam de 8,0 até 17,5 % equivalente de NaCl. Desde há muito sabe-se que a FFI contém pequenas quantidades de ouro. Assim como as porções manganesíferas da FFI, o ouro é supostamente um componente singenético que poderia ter sido primariamente concentrado. Metamorfismo e lixiviação hidrotermal da FFI mobilizaram o ouro, que foi posteriormente depositado nas proximidades da rocha fonte sedimentar enriquecida em ouro. Esta hipótese é tomada em preferência à lixiviação hidrotermal das rochas verdes arqueanas do Supergrupo Rio da Velhas (SGRV). A inexistência de mineralização paladiada no SGRV constitui evidência de que o paládio é um elemento particular a FFI O paládio é tentativamente correlacionado às porções singenéticas ricas em manganês da FFIAbstract: The Gongo Soco gold mine became famous around 1830 for its astonishing high grade gold ore. fu 30 years (1826-1856) the English company "Imperial Brazilian Mining Association" produced 12.887 kg of gold. . In spite of the economic and historical importance of the Gongo Soco mine its ore genesis is still poorly understood in part due to inaccessibility to the ancient underground workings. This study has aimed at the recently exposed auriferous bodies by iron ore mining at the Gongo Soco iron mine. The English enterprise wrought thin auriferous layers intermingled conformably to the adjoining soft high-grade haematite ore of the Lower Proterozoic Itabira iron formation (IIF) of the Quadrilátero Ferrífero (QF), Minas Gerais, Brazil. These bunches, known as jacutinga, were composed by specular haematite, talc, kaolinite and manganese oxide and characterized by absence of sulphide mineraIs. The linear disposition of the ore bodies towards east is assigned to the eastward dipping stretching lineation. Gold occurs typically as free particles or as inclusions within specular haematite, pyrolusite or goethite. Two stages of hydrothermal gold mineralization are envisaged: (i) an early stage synchronous with specular haematite and talc formation and (ii) a low temperature deposition together with goethite and pyrolusite. The impressive old descriptions of gold prills reaching few pounds seem to be related to mobility and enrichment in supergene environrnent as they were usually found near surface. Gold grain morphology varies from prolate and bent to rounded and faced forms. The prolate ones have been considered to be in response to stretching. Microprobe analyses of gold grains have confirmed the existence of palladium although in less quantities than those reported in the nineteenth century literature. Silver exceeds palladium contents up to five times. An intriguing dark palladium and iron-rich coating around gold grain is worthy of note. A highly oxidizing and acidic environment is assured upon the basis of the existence of specular haematite and kaolinite. Under these conditions (haematite-magnetite buffer) gold is expected to be transported as chloro complexes. An efficient depositing mechanism is achieved by reacting such a fluid with magnetite promoting its oxidation to haematite and precipitating gold species. The interface between impermeable hard haematite hanging-wall and cherty itabirite footwall would be a suitable path way to allow fluid flow and precipitation reactions. This scenario is congruous with the acidic and oxidizing metamorphism of the IIF in its cummingtonite zone. As temperature decreases, oxygen gets high enough to account for precipitation of manganese oxidelhydroxide and goethite along with gold. This later stage of gold mineralization, wherein gold is soluble as chloro complexes, is considered a remobilization of the higher temperature stage. Some fluid inclusion homogenization data near 130°C are compatible with the goethite-pyrolusite assemblage; salinities range from 8,0 to 17,5 % NaCI equivalent. It has long been known that the IIF contains small amounts of gold. Like the manganese-bearing portions of the IIF, gold is supposed to be a syngenetic component that could have been primarily concentrated elsewhere. Metamorphism and hydrothermal leaching of the IIF mobilized gold that was deposited in the proximity to the source sedimentary-enriched stratum. This hypothesis is taken in preference to the hydrothermalleaching of the Archaean greenstone rocks of the Rio das Velhas Supergroup (RVS). The inexistence of palladium mineralization in the RVS supports evidence that palladium is an element particular to the IIF. Palladium is tentatively correlated with the syngenetic manganese-rich portions of the IIFMestradoMetalogeneseMestre em Geociência
