DIamonds-+Alex+Brockhaus

Diamonds Diamonds are often used as jewelry. They are also used for drills and saws because they can cut through anything. Diamonds are also used for many decorations.
 * ~ Formula: ||||||  || C ||   ||
 * ~ System: || Isometric ||~ Colour: || Colourless, yellowish to ... ||
 * ~ Lustre: || Adamantine, Greasy ||~ Hardness: || 10 ||
 * ~ Name: |||||| From Greek "adamas", 'invincible'. First known use by Manlius (A.D. 16) and Pliny (A.D. 100). ||
 * ~ Polymorph of: |||||| [|Chaoite], [|Graphite], [|Lonsdaleite] ||
 * ~ Polymorph of: |||||| [|Chaoite], [|Graphite], [|Lonsdaleite] ||

Diamond is the hardest natural substance known. It is formed deep in the mantle, and is only brought to the surface via kimberlite pipes, lamprophyres, eclogites and other rocks that originate deep within the mantle. It is also found in alluvial deposits, along with quartz, corundum, zircon and other minerals, derived from such rocks, and in certain meteorites. http://www.mindat.org/min-1282.html

Perfect octahedral {111} ||
 * ==Physical Properties of Diamond== ||
 * ~ Lustre: || Adamantine, Greasy ||
 * ~ Diaphaneity (Transparency): || Transparent, Translucent, Opaque ||
 * ~ Colour: || Colourless, yellowish to yellow, brown, black, blue, green or red, pink, champagne-tan, cognac-brown, lilac (very rare) ||
 * ~ Streak: || none ||
 * ~ Hardness (Mohs): || 10 ||
 * ~ Hardness Data: || Mohs hardness reference species ||
 * ~ Tenacity: || Brittle ||
 * ~ Cleavage: || Perfect
 * ~ Fracture: || Irregular/Uneven ||
 * ~ Density (measured): || 3.5 - 3.53 g/cm3 ||
 * ~ Density (calculated): || 3.515 g/cm3 ||

Diamond is more common then perceived, although its environment is limited and most Diamonds found are not of the gem variety. South Africa is the largest producer of Diamond, and has several famous localities. Most notable is Kimberly, specifically the Kimberly Mine (also known as "The Big Hole"). The surrounding area also contains many productive Diamond mines. Two other famous mines in South Africa are the Premier Mine (Cullinan Mine), in Pretoria; and the Finsch mine in Northern Cape Province. Namibia (the coastal region), Sierra Leone, and the Congo are also important African producers of Diamond. Russia has the old and well-known Mir Pipe in Yakutsk. Two other notable worldwide occurrences are the Argyle mine in Western Australia; and Diamantina, Minas Gerais, Brazil, where Diamond is found in conglomerate.

In the U.S., there is a Diamond Mine located in the Crater of Diamonds State Park, near Murfreesboro, Pike Co., Arkansas. This is the only Diamond mine in the world open to the public, but on average only about 2 or 3 Diamonds are found per day. In California, in the [|Gold] producing regions of the Sierra Nevada Mountains, several limited occurrences have been noted especially where glaciers left waterworn pebbles in [|placer deposits] (such as in Trinity County). Kelsey Lake in Larimer Co., Colorado, contains the only commercially operating diamond mine in the U.S., and it was started in1996. A new Diamond field was also recently discovered in Lac de Gras in the Northwest Territories, Canada, with the Ekati and Diavik Diamond mines making Canada a new Diamond producer.

http://www.minerals.net/mineral/elements/diamond/diamond.htm