Learn · Hypothesis

Carbonado: the black diamond that may have come from the stars

Education only. Carbonado’s origin is unresolved and debated. Nothing on these pages describes, or is connected to, any Luxurious Specimens lot. No lot is claimed to be carbonado or to come from space.

Supernova 1987A, imaged by Hubble, shown for illustration. It is not the source of carbonado. Credit: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics). Source (CC BY 4.0).

Carbonado is a black, porous diamond made of countless tiny crystals bonded together. Portuguese prospectors in Brazil named it for its resemblance to charcoal^[1,2]. It is found only in Brazil and the Central African Republic^[1].

In 2006, Jozsef Garai, Stephen Haggerty and colleagues published infrared spectra of carbonado measured with synchrotron light at Brookhaven National Laboratory. They reported hydrogen and single-nitrogen signatures and compared the spectra with lab-grown and presolar diamonds, concluding that carbonado formed in a hydrogen-rich interstellar environment^[3,4]. The NSF release described the idea that carbonado formed in exploding stars and arrived in bodies a kilometer or more across^[1].

This is a hypothesis, not settled science. Other teams found that some infrared bands come from water and carbonate inside the diamond and proposed growth from fluids on Earth^[5,6]. Earth-based ideas also include meteorite impact into crustal rocks^[7], subduction, and radiation from uranium-rich carbon^[8]. A GIA review weighs these competing ideas^[2], while a fuller critique is in Haggerty’s 2014 review^[9].

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Sources

U.S. National Science Foundation news release (Jan. 9, 2007), “Diamonds from outer space: geologists discover origin of Earth's mysterious black diamonds,” via EurekAlert! https://www.eurekalert.org/news-releases/910688
Gems & Gemology (GIA), Summer 2017, “Carbonado Diamond: A Review of Properties and Origin.” https://www.gia.edu/gems-gemology/summer-2017-carbonado-diamond
Garai, J., Haggerty, S. E., Rekhi, S. & Chance, M. (2006). Infrared absorption investigations confirm the extraterrestrial origin of carbonado diamonds. The Astrophysical Journal Letters 653, L153–L156. https://doi.org/10.1086/510451
Brookhaven National Laboratory Newsroom (Jan. 10, 2007), “Diamonds from Outer Space.” https://www.bnl.gov/newsroom/news.php?a=110576
Ishibashi, H. et al. (2012). Hydrous fluid as the growth media of natural polycrystalline diamond, carbonado. American Mineralogist. https://doi.org/10.2138/am.2012.4097
“Infrared and Raman spectroscopic observations of Central African carbonado and implications for its origin” (2008). European Journal of Mineralogy. https://doi.org/10.1127/0935-1221/2008/0020-1817
Smith, J. V. & Dawson, J. B. (1985). Carbonado: Diamond aggregates from early impacts of crystal rocks? Geology 13(5), 342. https://doi.org/10.1130/0091-7613(1985)13%3C342:CDAFEI%3E2.0.CO;2
Daulton, T. L. & Ozima, M. (1996). Radiation-induced diamond formation in uranium-rich carbonaceous materials. Science 271, 1260–1263. https://doi.org/10.1126/science.271.5253.1260
Haggerty, S. E. (2014). Carbonado: Physical and chemical properties, a critical evaluation of proposed origins, and a revised genetic model. Earth-Science Reviews. https://doi.org/10.1016/j.earscirev.2013.12.008

Image credits

Background: Cassiopeia A (NIRCam image), weic2330a. Credit: NASA, ESA, CSA, STScI, D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent). Source (CC BY 4.0).
How the continents moved from Pangaea (250 million years ago) to today: U.S. Geological Survey, This Dynamic Earth: The Story of Plate Tectonics. Source (USGS, public domain).
Southern Florida’s Everglades: NASA Earth Observatory images by Jesse Allen, using Landsat data from the U.S. Geological Survey. Source (NASA, public domain).
Supernova 1987A: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics). Source (CC BY 4.0).
Carbon-rich dust shells around the star Wolf-Rayet 140: NASA, ESA, CSA, STScI, E. Lieb (University of Denver), R. Lau (NSF NOIRLab), J. Hoffman (University of Denver). Source (CC BY 4.0).
Manicouagan Crater: NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Source (NASA, public domain).
The Pilbara Craton in Western Australia (false color): NASA Earth Observatory image by Joshua Stevens, using data from NASA/METI/AIST/Japan Space Systems, and the U.S./Japan ASTER Science Team. Source (NASA, public domain).
The Atlantic between Brazil and Africa today: NASA Earth Observatory image by Joshua Stevens, using imagery from the Deep Space Climate Observatory (DSCOVR). Source (NASA, public domain).
Dzanga Bai: NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey and data from OpenStreetMap (OSM map data © OpenStreetMap contributors, ODbL). Source (NASA, public domain; map data ODbL).
Skully photos (asa-specimen-01, 02, 03, 08 and asa-skully-scale): ASA Digital Art (own photos of one ASA specimen, Skully, under different lighting and angles; the scale photo is cropped with the scale branding blurred; not identified as carbonado; no origin is claimed; not a lot for sale).
Other specimen photos (asa-specimen-07, 09, 10): ASA Digital Art (own photos of ASA specimens, background removed; not identified as carbonado; no origin is claimed; not lots for sale).
Gravel photos (asa-gravel-04, 05, 06): ASA Digital Art (own photos of crushed sediment and gravel; no site named). Collected lawfully over about a decade as a personal hobby, on break and lunch time while working on construction projects, with authorization to remove non-building material that would otherwise have been thrown out or buried under pavement; not from any park, preserve or public land where collecting is restricted.
Red-hot images (asa-specimen-09-redhot, asa-specimen-10-redhot): Digitally edited illustration based on a photo of an ASA Digital Art specimen. The red-hot glow was added digitally to picture the plasma-channel idea; the specimen was not heated and does not look like this. Not identified as carbonado; no origin is claimed. Speculative. Made locally from ASA Digital Art photos.
Fossil tooth photo: ASA Digital Art (own photo of a fossil found with ASA specimens; appears to be a Megalodon tooth; not a lot for sale).
1200x microscope photo: ASA Digital Art (own photo of an ASA specimen; not identified as carbonado; not a lot).
Images labeled “Illustration (digital render)” are artwork made for this page. They are not photographs and do not show actual specimens or any lot.

ESA/Hubble and ESA/Webb images are used under CC BY 4.0. Use of these images does not imply endorsement by ESA, NASA, CSA or STScI. NASA images are public domain and credited as requested.