From Graphite To Diamond Essay Research Paper

From Graphite To Diamond Essay, Research Paper

From Graphite to Diamond

The Whole Journey

It is a long journey for a piece of graphite to transform into a beautiful diamond. It only takes a little energy ( 1.9 K/j mole ) but it is a very difficult process. To create a diamond you must have temperatures ranging from room temperature to four thousand degrees Celsius, but the big factor is that you must have at least one-hundred thousand and upwards of a million pounds of pressure per square inch (Sass). Diamonds are born 50 miles below Earth’s surface, in the hot mantle, where a pressure of 55,000 atmospheres and a temperature near 2,700 degrees Fahrenheit pound away at the graphite to turn it into a beautiful diamond (Preiser 22).

Diamonds were formed millions of years ago in molten lava. As the lava flowed to the Earth’s surface through vents known as pipes, it cooled and solidified into kimberlite, a blue rock. Kimberlite contains the diamonds and is known to diamond miners as blue ground (Comptons).

Diamonds have been found on all continents. India was once a chief source. In about AD 600 diamonds were found in Borneo and are still mined there. The rich fields of Brazil were discovered in the 1700s. In the 19th century even richer diamond fields were found in South Africa. Most of the world’s diamonds are mined in African countries. Zaire produces mostly industrial diamonds. South Africa is the major source of gem-quality diamonds. Congo, Ghana, Namibia, and Angola are other major suppliers. Russia has diamond-mining operations in northeastern Siberia. Since the late 1970s many diamonds have been found in Australia (Comptons).

About 20 percent of the world’s output is used for industrial purposes, with the United States importing some 60 percent of the industrial diamonds mined. A few diamonds are found in Pike County, Ark., and diamonds have also been found in the Upper Peninsula of Michigan. (Comptons)

The diamond is one of the world’s most important mineral resources, it is made of pure, natural carbon with the atoms organized in a close-packed cubic arrangement that gives the stones their hardness. In fact the diamond is four times harder than the next hardest natural mineral, which is corundum.(3) But as hard as the diamond is, there is one small weakness. The diamond has four directions of cleavage. So if it receives a sharp blow to any of these four points it will break. The common crystal form is the octahedron, which looks like two four- sided pyramids placed base to base. Since diamond is so much harder than any other natural or artificial substance known, it is ideal for both gem and industrial purposes. Special optical properties guarantee its superiority among gems. First, its high light-bending ability enables it to throw back almost all the light that enters a well-cut gem. This gives rise to the gem’s brilliant luster. Second, it exhibits the ability to separate the various colors of the spectrum. This causes the gem to throw back the bright flashes of separated colors for which it is particularly noted. Also the diamond is the world s be heat conductor (Diamond Comments).

Diamond is composed of the single element carbon, and it is the arrangement of the carbon atoms in the lattice that give diamond its amazing properties. Compare the structure of diamond and graphite, both composed of just carbon. In diamond we have the hardest known material, in graphite we have one of the softest, simply by rearranging the way the atoms are bonded together (May).

Graphite Lattice Diamond Lattice

The relationship between diamond and graphite is a thermodynamic and kinetic one. At normal temperatures and pressures, graphite is only a little more stable than diamond, and the fact that diamond exists at all is due to the very large activation barrier for conversion between the two. There is no easy mechanism to convert between the two and so interconversion requires almost as much energy as destroying the entire lattice and rebuilding it (Field 54). Once diamond is formed, therefore, it cannot convert back to graphite because the barrier is too high. So diamond is said to be metastable, or relatively unstable. Diamond is created deep underground under conditions of extreme pressure and temperature. Under these conditions diamond is actually the more stable of the two forms of carbon ( graphite and diamond ), and so over a period of millions of years carbonaceous deposits slowly crystallize into single crystal diamond gemstones (Bundy 15,16).

Here are some of the physical characteristics of the diamond:

h Color- is variable and tends toward pale yellows, browns, grays, and also white, blue, black, reddish, greenish and colorless.

h Luster- is adamantine to waxy.

h Transparency- crystals are transparent to translucent in rough crystals.

h Crystal System- is isometric; 4/m bar 3 2/m

h Crystal Habits- include isometric forms such as cubes and octahedrons, twinning is also seen.

h Hardness- is 10

h Specific Gravity- is 3.5 (above average)

h Cleavage- is perfect in 4 directions forming octahedrons.

h Fracture- is conchoidal.

h Streak- is white.

h Associated Minerals- are limited to those found in kimberlite rock, an ultramafic igneous rock composed mostly of olivine.

h Other

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