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Chemical Formula | C |
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Composition | Carbon |
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Color | Colorless and white, usually lightly tinged
with yellow, orange or brown. Less commonly blue, green,
or red. Rarely deep red, blue, green, or purple. Also occurs dark gray to black. |
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Streak | White |
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Hardness | 10 |
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Crystal Forms and Aggregates |
(Isometric) Usually octahedral, often with many crystal faces. Dodecahedral crystals, although less common, also occur. Cubic crystals are rarer. Crystals almost always have curved faces, and in some cases, they appear round. |
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Transparency | Transparent to Opaque |
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Specific Gravity | 3.1 - 3.53. Pure crystals are almost always 3.52. Carbonado is 3.1 - 3.3 |
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Luster | Adamantine. Rough stones have a greasy luster. |
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Cleavage | 1, all sides - octahedral. Dodecahedral Diamonds, Borts, and Carbonado exhibit poor or no cleavage. |
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Fracture | Conchoidal |
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Tenacity | Brittle |
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Other ID Marks | 1) Commonly fluorescent in shortwave ultraviolet light;
usually light blue, sometimes white, yellow, orange, and
red. 2) Has a cold feel. |
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Varieties |  Ballas - Mass of tiny
Diamonds compacted together to form a spherical shaped
aggregate. Bort
- Dark Colored, imperfectly crystallized Diamond, that is
translucent to opaque. In the Diamond trade, a Bort is
also a fragment of a gem quality Diamond. Carbonado
(or Black Diamond) - Dark gray to black
Diamond, opaque, exhibits no cleavage, and has a specific
gravity of 3.1 - 3.3. Hexagonal Diamond - Synonym
of Lonsdaleite |
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Polymorphs | Graphite, Lonsdaleite, Chaoite |
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In Group | Native elements ; Nonmetallic elements |
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All About | Diamond has many unequaled qualities. It is
the hardest known substance, it is the greatest conductor of
heat, it has the highest melting point of any substance (7362° F - 4090° C), and
has the highest refractive index of any natural mineral. Diamond is number 10 on the Mohs scale, and is 40 times harder than Corundum, which is number 9 on the Moh's scale (and the next hardest natural substance).
It also has the most dense atomical
configuration of any minerals, and is transparent over the greatest
number of wavelengths. Because of heat conduction, Diamonds are cold to the feel at
or below room temperature. When heated, a Diamond will remain hot long after the heat source is removed. The luster of Diamonds is excellent. Diamond exhibits great "fire", or brilliance, which gives it a shiny, freshly polished look. Rough Diamonds exhibit a greasy luster, but proper cutting give them a powerful adamantine luster. Only synthetic substances and a few minor gemstones can reach or excel the refractive index of Diamonds. The hardness and refractive index may slightly vary among Diamond specimens. Bort and Carbonado exhibit a slightly lower hardness than other Diamonds, and lack cleavage. Lonsdaleite (or Hexagonal Diamond), is a type of Diamond found with meteorites and is of extraterrestrial origin. It is scientifically a different mineral than Diamond, and believed to have formed when meteoric Graphite fell to earth. When this happened, great heat and stress transformed the Graphite into Diamond, but it retained Graphite's hexagonal crystal lattice. |
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Uses | The most notable use of Diamonds is in the
jewelry market. Due to its brilliance, hardness, and
rarity of Diamond, it is the most famous of all gems. Only about 20 percent of Diamonds are fit for gem use. The other 80 percent mined are used as abrasives, as thermal insulators, in optics, and in electronics. Also see the gemstone section on Diamond |
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Striking Features | Immense hardness, adamantine luster, and specific localities |
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Complex Tests | Diamond is the most inert and durable material, and is not effected by any chemicals. |
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Popularity (1-4) | 1 |
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Prevalence (1-3) | 3 |
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Demand (1-3) | 1 |
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Distinguishing Similar Minerals |
The only mineral that can possibly be be confused with Diamond is waterworn Quartz pebbles which resemble waterworn Diamonds, but the hardness and luster of Diamond will differentiate the two. |
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Commonly Occurs With |
Olivine, Magnetite, Pyrope, Phlogopite, (Kimberlite) |
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Noteworthy Localities |
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. |
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