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| Format: | Artículo científico |
| Language: | en |
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Academia Brasileira de Ciências
2007
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| Online Access: | https://www.redalyc.org/articulo.oa?id=32779408 |
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Table of Contents:
- Coexistence of halloysite and kaolinite - a study on the genesis of kaolin clays of Campo Alegre Basin, Santa Catarina State, Brazil Milton L. L. Formoso Norberto Dani Marisa Terezinha Garcia de Oliveira Sandra M.A. Furtado Richard A. Eggleton Multidisciplinaria (Ciencias Naturales y Exactas) kaolin kaolinite halloysite weathering clay genesis Kaolin atCampoAlegre Basin, SantaCatarina State,Brazilwas formed from alteration of volcanic acid rocks. Halloysiteclays dominate the clay fraction of the matrix of the kaolin body, whereas a poorly crystalline kaolinite is abundantin veins. Some primary blocky structures have high amounts of illite, in one mine, but in general, only low contentsof illite-smectite, illite, chlorite-vermiculite, vermiculite and quartz were identified in the clay fraction of the samples.Toward the top of the mines, hematite and lepidocrocite appear in horizontal red and ochre colored levels and the amountof kaolinite increases compared to halloysite. The vertical zoning of alteration levels, the changes in mineralogy, thepositive correlation between depth and Cation Exchange Capacity of the clays, the preservation of different types ofrock textures in the kaolin bodies, the dominant tube morphology of the halloysite clays indicate a supergene genesisfor the deposits. Criteria to distinguish between supergene and hypogene kaolin are discussed. Transmission ElectronMicroscopy of the cross sections of halloysite tubes showed polygonal forms that are ascribed to be transitional betweenkaolinite and halloysite. It is proposed that some of the kaolinite of these deposits be inherited from the dehydration ofhalloysite tubes. 2007 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32779408 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.79