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|Type:||Artigo de periódico|
|Title:||Ochreous Laterite: A Nickel Ore From Punta Gorda, Cuba|
|Abstract:||The 'ochreous laterite' is the oxidised nickel ore from the Punta Gorda deposit, Cuba. Mössbauer spectroscopy, X-ray diffraction (XRD), thermal methods and selective extraction techniques have been used to characterise the ore. The ore consists mainly of poorly crystalline A1-substituted goethite. The poor crystallinity of goethite is demonstrated by broad lines in the diffraction patterns and hence, low mean crystalline dimension (MCD) values, low dehydroxylation temperatures, high weight losses between 100 and 1000°C, and the magnetic hyperfine field distribution. Also present in the ore are minor quantities of hematite, gibbsite, chromite, and manganese minerals. Most of the nickel is associated with goethite. Cobalt is mainly associated with the manganese minerals. The Ni-rich ore, with contents of Fe 2O 3 between 72.1 and 77.2% and contents of Ni between 1.6 and 2.1%, is probably derived from a peridotite bedrock containing, in addition to olivine, Ni-bearing orthopyroxenes. Peridotite containing Al-clinopyroxene might be, on the other hand, the parent rock of the Ni-poor ore, with Fe 2O 3 contents between 42.6 and 62.6% and Ni contents between 0.24 and 0.96%. © 2001 Elsevier Science Ltd. All rights reserved.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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