黑鑽石（；又稱黑金剛石或圓粒金剛石）是韌性最強的的天然金剛石之一。它是一種不純淨、密度高的多孔隙多晶粒鑽石，由金剛石、石墨及無定形碳組成，孔隙內或會有微小晶粒沉澱物或已還原的金屬包裹體填充，使其呈各種色彩。黑鑽石主要發現於中非共和國及巴西的中海拔沖積礦床。它的自然顏色是黑色或暗灰色，孔隙率比其它鑽石高。 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。 黑鑽石一般都是由豌豆大小或更大的多孔微小的黑色晶體的聚合體。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巖中發現。利用黑鑽石晶體內的鉛，發現這些晶體約於 3 億年前形成；然而，黑鑽石卻只發現於年輕的沉積岩中。 鑽石中包含的礦物顆粒已被廣泛研究，以尋找鑽石來源的線索。一些典型的鑽石含有常見的地幔礦物包裹體，如和鎂橄欖石，但在黑金剛石中尚未觀察到此類地幔礦物。相比之下，一些碳酸鹽含有地殼特徵礦物的自生包裹體；內含物不一定確定地殼中鑽石的形成，因為雖然明顯的晶體內含物出現在黑鑽石中常見的孔隙中，但它們可能是在黑鑽石形成後引入的。發現地殼中稀有或幾乎不存在的其他礦物的夾雜物至少部分包含在金剛石中，而不僅僅是在孔隙中：在這些其他礦物中，含有矽、碳化矽及鐵鎳的成分。沒有發現獨特的高壓礦物，包括六方碳的同質異形體藍絲黛爾石，作為夾雜物出現在黑鑽石中，儘管黑鑽石有可能是由隕石撞擊而形成的。 同位素的研究揭示更多關於黑鑽石來源的線索：黑鑽石內碳的同位數慎非常低，相比一般的鑽石，黑鑽石內碳 13 比碳 12 少得很多。 Carbonado exhibits strong luminescence 光致發光 and 陰極射線發光 induced by 氮 and by 晶格空位 existing in the crystal lattice Luminescence halos are present around radioactive inclusions and it is suggested that the radiation damage occurred after formation of the carbonados an observation perhaps pertinent to the radiation hypothesis listed below Toughness vs hardness Carbonados polycrystalline texture makes it more durable than a monocrystalline diamond It is the same hardness as other types of diamond but it is much tougher Its polycrystalline texture allows a single abrasive granule to present multiple crystallographic orientations of the diamond crystal at the cutting surface and the hardest orientation does the most aggressive cutting Cutting tools made with carbonado diamond last longer and require less maintenance Carbonado was recognized as a super abrasive in the 1800s and was more highly valued for its cutting and grinding effectiveness over other varieties of diamond The problem with carbonado is its rarity It is only found in two countries and total worldwide production has only been a few tons of material Carbonado is not an important commodity in todays abrasive market In the late 1800s when De Beers was developing their diamond mines in South Africa they preferred carbonado over their own diamonds for diamond drilling Gardner F Williams General Manager of De Beers Consolidated Mines Ltd lamented Round or shot is found in the mines at Kimberley and is very valuable for use in diamond drilling since the Brazilian carbonado has become so scarcecite websiteauhorHobart M King PhD GIA Graduate Gemologistyear2022httpsgeologycomdiamondcarbonado 起源假說 黑鑽石的起源有爭議，以下列出部分建議的起源假說： 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，但現時僅發現於部分地區。 ，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。 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（指直徑 05 毫米以上）的金剛石。 由於與長時間的超級閃電雷擊相關的火變質快速過程，在漫長的地質時期中，在減少的富含有機物沉積物中累積的區域性形成，已知與相似海拔的碳金剛石礦床具有相似的全球分佈。 形成於一顆在太陽系區域附近的前代巨型恆星內部，然後透過超新星爆發來到地球。 起源於星際物質，由於小行星的撞擊落到地球，而非源於爆發的恆星內部。 研究顯示這些黑鑽石的紅外線吸收頻譜與地外來源的鑽石的吸收頻譜近似； selected significant peaks are due to trace abundances of the elements 氮 and 氫 The researchers concluded with the assumption that the mineral necessarily formed in an interstellar environment In this sense carbonado are theorized to be akin to carbonrich 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 截至 2008 年，上述六個有關黑鑽石形成的假說都未有得到廣泛認同；此外，有關黑鑽石內碳 13 和碳 12 的比例亦與當地沉積物的比例相同。 地外起源假說 黑鑽石地外起源假說的支持者認為黑鑽石源於 380 億年前一顆超新星爆炸時噴射出來的物質。After coalescing and drifting through 外層空間 for about one and a half billion years a large mass fell to earth as a 隕石 approximately 23 billion years ago It possibly fragmented during entry into the Earths atmosphere and impacted in a region which would much later 板塊構造論 into 巴西 and the 中非共和國，assumed to be the only two known locations of carbonadodiamond deposits which is not an accurate representation of the distribution of carbonado diamondite the polycrystaline form 不過介乎兩個國家之間的喀麥隆並未有黑鑽石開採過的紀錄。 最大已切割鑽石 現時世上最大的已切割鑽石是一顆名為「」的黑鑽石，達到 55555 克拉，擁有 55 個切面，目前估價為 500 萬英鎊（約新臺幣 188 億元）。 參見 超硬材料 參考資料 外部連結 Photo of porous carbonado at National Science Foundation Photo of glossy carbonado and article on possible extraterrestrial origins at PBS Nova Mystery Diamonds Geoscientists Investigate Rare Carbon Formation ScienceDaily June 1 2007 Story Category 鑽石