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carbonado

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Journal Article
Published: 01 January 2018
European Journal of Mineralogy (2018) 30 (1): 61–76.
... removal followed by diffusion-limited crystallization of pure carbon. The similarity of the after-coal diamonds features with carbonado is a strong piece of evidence in support of the impact hypothesis for the origin of carbonado. © 2018 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart 2018...
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Journal Article
Journal: Geology
Published: 01 July 2016
Geology (2016) 44 (7): 527–530.
...Charles W. Magee, Jr.; Guilherme Teles; Edward P. Vicenzi; Wayne Taylor; Peter Heaney Abstract Carbonado is a porous polycrystalline diamond rock found in central African and Brazilian placer deposits. It contains unsupported radiogenic isotopes of He, Ne, Kr, Xe, and Pb. Here we show...
FIGURES
Journal Article
Journal: Geosphere
Published: 01 October 2013
Geosphere (2013) 9 (5): 1336–1347.
...Richard A. Ketcham; Christian Koeberl Abstract Three-dimensional textural observations of inclusion and porosity patterns in a 23-carat carbonado diamond using high-resolution X-ray computed tomography reveal new information bearing on the nature and origin of this enigmatic material. A prominent...
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Journal Article
Published: 01 September 2013
European Journal of Mineralogy (2013) 25 (3): 373–383.
... phase is transformed by a diffusionless mechanism into a cubic structure at pressures of around 6.5 GPa. A diamond-like BCN phase was synthesized in the form of individual crystals or polycrystalline aggregates. The microstructure of these aggregates is comparable to natural and synthetic carbonado-type...
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Journal Article
Published: 01 February 2013
The Canadian Mineralogist (2013) 51 (1): 39–56.
...Felix V. Kaminsky; Richard Wirth; Luiz Morales Abstract Samples of carbonado from Brazil and the Central African Republic were studied with the use of electron backscatter diffraction (EBSD) for quantitative textural analysis (QTA) and transmission electron microscopy (TEM). The grain size...
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Journal Article
Published: 01 August 2012
American Mineralogist (2012) 97 (8-9): 1366–1372.
...Hidemi Ishibashi; Hiroyuki Kagi; Haruko Sakuai; Hiroaki Ohfuji; Hirochika Sumino Abstract Carbonado, a variety of natural polycrystalline diamond whose origin remains unknown, differs notably in the properties from common diamonds of mantle origin. In this study, infrared spectroscopic...
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Journal Article
Published: 01 October 2011
European Journal of Mineralogy (2011) 23 (5): 721–729.
...Violaine Sautter; Jean-Pierre Lorand; Patrick Cordier; Benjamin Rondeau; Hugues Leroux; Cristiano Ferraris; Sylvain Pont Abstract A unique Brazilian sample of a carbonado, displaying unusually large amount of diamond clasts merged within a fine-grained diamond matrix, has been studied by Secondary...
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Journal Article
Published: 01 January 2010
European Journal of Mineralogy (2010) 22 (1): 35–47.
...Vitaly A. Petrovsky; Andrei A. Shiryaev; Vladimir P. Lyutoev; Alexander E. Sukharev; Maximiliano Martins Abstract The morphology and defects in diamond grains comprising Brazilian carbonado have been investigated using X-ray diffraction, photo- and X-ray luminescence, electron paramagnetic...
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Journal Article
Published: 01 October 2008
The Canadian Mineralogist (2008) 46 (5): 1283–1296.
...Reika Yokochi; Daniel Ohnenstetter; Yuji Sano Abstract We have investigated the textural diversity in four Brazilian samples of carbonado diamond by cathodoluminescence petrography and spectroscopy, coupled with carbon, nitrogen and argon isotope analyses. Three types of textures were observed...
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Journal Article
Published: 01 June 2008
European Journal of Mineralogy (2008) 20 (3): 387–393.
...Hiroyuki Kagi; Satoshi Fukura Abstract Carbonado diamonds from the Central African Republic (CAR) were investigated using spectroscopic observations. Raman spectra for a polished section of carbonado showed the average Raman frequency as 1333.0 cm −1 ; measurements 10 μm below the sample surface...
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Journal Article
Published: 01 January 2007
American Mineralogist (2007) 92 (1): 217–224.
...Hiroyuki Kagi; Shuichi Sato; Tasuku Akagi; Hisao Kanda Abstract Carbonado diamonds from the Central African Republic were investigated using spectroscopic observations and C-isotopic analysis. Based on photoluminescence (PL) spectra, carbonado samples were classified into two groups: Group-A, which...
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Journal Article
Journal: Elements
Published: 01 March 2005
Elements (2005) 1 (2): 67–70.
...—carbonado and framesite—and, second, microdiamonds discovered over the last 20 years associated with metamorphic rocks. Heaney, Vicenzi, and De review the characteristics of carbonado and framesite and help unravel some of the mystery around these enigmatic materials. As a high-pressure mineral, diamond...
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Journal Article
Journal: Elements
Published: 01 March 2005
Elements (2005) 1 (2): 85–89.
...Peter J. Heaney; Edward P. Vicenzi; Subarnarekha De Abstract Polycrystalline aggregates of diamond called carbonado and framesite have excited the attention of scientists because their crystallization histories are thought to depart markedly from established modes of diamond genesis. In contrast...
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Journal Article
Published: 01 February 2004
American Mineralogist (2004) 89 (2-3): 438–445.
...Subarnarekha De; Peter J. Heaney; Yingwei Fei; Edward P. Vicenzi Abstract Efforts to simulate the extreme toughness of the polycrystalline diamond variety known as carbonado typically entail the sintering of diamond powders in the presence of metal solvent-catalysts. In this study, we have...
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Journal Article
Published: 01 January 2003
American Mineralogist (2003) 88 (1): 11–17.
...V.A. Nadolinny; V.S. Shatsky; N.V. Sobolev; D.J. Twitchen; O.P. Yuryeva; I.A. Vasilevsky; V.N. Lebedev Abstract Electron paramagnetic resonance (EPR) and photoluminescence (PL) spectroscopies have been used to study Brazilian and Central African carbonados. We report the first observation of the N...
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Journal Article
Journal: Geology
Published: 01 May 1985
Geology (1985) 13 (5): 342–343.
...J. V. Smith; J. B. Dawson Abstract Carbonados are irregular polycrystalline aggregates of diamond that occur in placers and low-grade metamorphic rocks. They are characterized by fine grain size, light carbon isotope ratio, a wide variety of inclusions of crustal materials (silicates, phosphates...
Journal Article
Published: 01 August 1971
American Mineralogist (1971) 56 (7-8): 1252–1268.
...Lucien F. Trueb; E. Christiaan De Wys Abstract Carbon originating from Ubangi (Central African Republic) is a dark-colored variety of polycrystalline diamond resembling Brazilian carbonado. It consists of a porous matrix of randomly oriented, mainly anhedral crystallites ranging from 0.5 to 20 μm...
Journal Article
Published: 01 April 1969
American Mineralogist (1969) 54 (3-4): 412–425.
...L. F. Trueb; W. C. Butterman Abstract Brazilian carbonados consist of mostly anhedral, randomly oriented diamond crystallites with a size ranging from a fraction of a micron to over 20 μm. These crystallites are aggregated and interlocked into porous polycrystalline masses with a microstructure...