黑鑽石

黑鑽石（又稱黑金剛石、圓粒金剛石或Carbonado）是一種發現在中非共和國及巴西沖積礦床的天然多晶金剛石。它的自然顏色是黑色或暗灰色，比其它鑽石有更多更孔隙。


不尋常的性質

除了另行說明外，黑鑽石的特點在這部分是由Heaney et al. (2005)的摘要指出。

黑鑽石由於有許多微小的黑色晶體，通常有豌豆大小或更大的聚合多晶體。最獨特的是，只有中非共和國及巴西能發現黑鑽石，極小部分發現在南非共和國，但卻沒有在通常發現鑽石的慶伯利岩中發現。鉛同位素分析晶體約於3億年前形成，在年輕的沉積岩中。

起源

黑鑽石的起源有重大的爭議，部分的假計如下：

  1. 有機碳在地球內部的高壓下直接轉換，如最常見的鑽石形成假說。這樣黑鑽石應該能於全球發現，但僅發現於部分地區。
  2. 衝擊變質，如隕石在地球表面衝擊引起的。但是，絕大部分衝擊引成的六晶體都是六方金剛石，與黑鑽石不同。
  3. 自發裂變的鈾和釷輻射誘發的形成。但輻射產生的分裂能量太小，不能創造大顆粒晶體的金剛石（500微米）。
  4. Formation inside an earlier-generation giant star in our area, that would have long ago exploded in a supernovae.[1]
  5. An origin in interstellar space, due to the impact of a supernovae, rather than being thrown from within an exploding star.[2]

參見

參考資料
  1. Garai, J., Haggerty, S. E., Rekhi, S., and Chance, M., 2006, Astrophysical Journal Letters, vol 653, pp L153-L156 . [2007-07-30]. （原始内容存档于2007-08-09）. Infrared Absorption Investigations Confirm the Extraterrestrial Origin of Carbonado-Diamonds This study suggested that infrared absorption spectra of carbonado are like those of diamonds of extraterrestrial origin; the significant peaks are due to trace abundances of the elements nitrogen and hydrogen.
    The researchers concluded that the mineral formed in an interstellar environment. 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 suggested to have been fragments of a body of asteroid size that subsequently fell to Earth as meteorites.
  2. Garai, J., Haggerty, S. E., Rekhi, S., and Chance, M., 2006, Astrophysical Journal Letters, vol 653, pp L153-L156 . [2007-07-30]. （原始内容存档于2007-08-09）. Infrared Absorption Investigations Confirm the Extraterrestrial Origin of Carbonado-Diamonds This study suggested that infrared absorption spectra of carbonado are like those of diamonds of extraterrestrial origin; the significant peaks are due to trace abundances of the elements nitrogen and hydrogen.

外部連結
维基文库中的《1911年版大英百科全書》條目：Carbonado
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