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Carbonado, commonly known as the 'Black Diamond,' is a natural polycrystalline diamond found in alluvial deposits in the Central African Republic and Brazil. Its natural colour is black or dark grey, and it is more porous than other diamonds.
Additional recommended knowledge
Unlike other natural polycrystalline diamonds, carbonado has no mantle-derived inclusions and its carbon isotope value is very low. Additionally, carbonado exhibits strong luminescence (photoluminescence and cathodoluminescence) induced by nitrogen and by vacancies existing in the crystal lattice. Analysis of the luminescence suggests that radioactive inclusions existed in the formation process of carbonado. These and other characteristics that separate the carbonado from other diamonds have led to questions as to the carbonado's origin.
Early theories on origin
The origin of carbonado is controversial, with several hypotheses proposed:
A team of U.S. geologists have published evidence relating to a different origin of these black diamonds: interstellar space. They have found that black diamonds contain trace elements of nitrogen and hydrogen which they claim are sure indicators of an extraterrestrial origin.
The study published in 2006 by Stephen Haggerty and Jozsef Garai, of Florida International University, analyzed the hydrogen in black diamond samples using infrared-detection instruments at the Brookhaven National Laboratory. The researchers found that the chemical properties of carbonado indicated that the mineral formed in a supernova explosion that took place prior to the formation of our Solar System.
In this sense, carbonado are theorized to be akin to carbon-rich cosmic dust, likely having formed in an environment near carbon stars. The diamonds were eventually incorporated into solid bodies that subsequently fell to Earth as meteorites.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Carbonado". A list of authors is available in Wikipedia.|