Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites
Gibbsite is a common mineral, present in several soil classes around the globe, especially in the tropical belt. It is also a key mineral in bauxite, the main natural source of aluminum. The occurrence of gibbsite in the soil greatly influences its physical and chemical characteristics. However, lit...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-11-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/12/11/1441 |
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| author | Arthur Stefanelli Gasparini Maurício Paulo Ferreira Fontes Anderson Almeida Pacheco João Carlos Ker |
| author_facet | Arthur Stefanelli Gasparini Maurício Paulo Ferreira Fontes Anderson Almeida Pacheco João Carlos Ker |
| author_sort | Arthur Stefanelli Gasparini |
| collection | DOAJ |
| description | Gibbsite is a common mineral, present in several soil classes around the globe, especially in the tropical belt. It is also a key mineral in bauxite, the main natural source of aluminum. The occurrence of gibbsite in the soil greatly influences its physical and chemical characteristics. However, little is known about the important structural properties of this mineral, which determines how these characteristics will be expressed. In this work, we investigated the variation in the morphology and crystallinity of naturally occurring gibbsites from soils and bauxites. The crystallinity of the gibbsite was assessed using full width at half maximum (FWHM), mean crystallite dimensions (MCD), and deoxydylation temperature (DT) measurements. The results of these analyses were convergent, indicating a better crystallinity for gibbsites from the evaluated Amazon soils and bauxites, and worse crystallinity for the remaining soil samples. SEM analysis was used to assess the gibbsite morphology, and X-ray diffraction data were used to propose an orientation index for this mineral. The results indicated that there is little to no isomorphic substitution of Al by Fe in natural gibbsites, there is a prevalence of larger crystals, with a more laminar morphology, with orientation capability for the gibbsites of Amazon soils and bauxites, and smaller crystals tending to spherical shape for the other samples. These results suggest that natural gibbsite crystals of good crystallinity have large crystals with a laminar shape, while crystals of lower crystallinity present a smaller size and approximately an isodiametric shape. |
| first_indexed | 2024-03-09T18:07:48Z |
| format | Article |
| id | doaj.art-441e392be9fe44ccbfcd220cf6cf4fd1 |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-09T18:07:48Z |
| publishDate | 2022-11-01 |
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| record_format | Article |
| series | Minerals |
| spelling | doaj.art-441e392be9fe44ccbfcd220cf6cf4fd12023-11-24T09:18:22ZengMDPI AGMinerals2075-163X2022-11-011211144110.3390/min12111441Gibbsite Crystallinity and Morphology in Ferralsols and BauxitesArthur Stefanelli Gasparini0Maurício Paulo Ferreira Fontes1Anderson Almeida Pacheco2João Carlos Ker3Soil Department, Federal University of Viçosa, Viçosa 36570-900, Minas Gerais, BrazilSoil Department, Federal University of Viçosa, Viçosa 36570-900, Minas Gerais, BrazilSoil Department, Federal University of Viçosa, Viçosa 36570-900, Minas Gerais, BrazilSoil Department, Federal University of Viçosa, Viçosa 36570-900, Minas Gerais, BrazilGibbsite is a common mineral, present in several soil classes around the globe, especially in the tropical belt. It is also a key mineral in bauxite, the main natural source of aluminum. The occurrence of gibbsite in the soil greatly influences its physical and chemical characteristics. However, little is known about the important structural properties of this mineral, which determines how these characteristics will be expressed. In this work, we investigated the variation in the morphology and crystallinity of naturally occurring gibbsites from soils and bauxites. The crystallinity of the gibbsite was assessed using full width at half maximum (FWHM), mean crystallite dimensions (MCD), and deoxydylation temperature (DT) measurements. The results of these analyses were convergent, indicating a better crystallinity for gibbsites from the evaluated Amazon soils and bauxites, and worse crystallinity for the remaining soil samples. SEM analysis was used to assess the gibbsite morphology, and X-ray diffraction data were used to propose an orientation index for this mineral. The results indicated that there is little to no isomorphic substitution of Al by Fe in natural gibbsites, there is a prevalence of larger crystals, with a more laminar morphology, with orientation capability for the gibbsites of Amazon soils and bauxites, and smaller crystals tending to spherical shape for the other samples. These results suggest that natural gibbsite crystals of good crystallinity have large crystals with a laminar shape, while crystals of lower crystallinity present a smaller size and approximately an isodiametric shape.https://www.mdpi.com/2075-163X/12/11/1441gibbsitekaolinitecrystallinitymorphologytropical soilsbauxite |
| spellingShingle | Arthur Stefanelli Gasparini Maurício Paulo Ferreira Fontes Anderson Almeida Pacheco João Carlos Ker Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites Minerals gibbsite kaolinite crystallinity morphology tropical soils bauxite |
| title | Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites |
| title_full | Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites |
| title_fullStr | Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites |
| title_full_unstemmed | Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites |
| title_short | Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites |
| title_sort | gibbsite crystallinity and morphology in ferralsols and bauxites |
| topic | gibbsite kaolinite crystallinity morphology tropical soils bauxite |
| url | https://www.mdpi.com/2075-163X/12/11/1441 |
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