A diamond is considered to be one of the most precious and rare stones on earth. These stones “are rare for three reasons: they form deep within the Earth in very localized places beneath continents, an extremely unusual kind of volcanic activity is needed to bring [diamonds] to the surface, and only about 20 per cent of them are gem quality” (Fleet, Hart, Wall 23). Not all diamonds are good enough to sell for jewelry purposes but are good for different industrial uses.
Many extensive geological processes are involved in the formation of diamonds as well as long periods of time needed. Diamonds which are mined formed about three billion years ago” (Fleet, Hart, Wall 23). The processes that occur in diamond formation are not completely known but different geologic evidence indicates certain processes that have taken place. Most areas that contain a significant amount of diamonds are older areas within the earth’s crust containing magmatic basaltic rocks. Diamonds are mostly found in kimberlite pipes. A kimberlite forms in the mantle within the earth along with a substantial amount of volatiles.
A “free carbon system” is also an essential need in the formation of diamonds.Between the extreme temperature and pressure along with the volatiles (possibly water and carbon dioxide), the magma pushes upward and forms a pipe that is compared in shape to a carrot. The actual pipe forms in that process. This is a rare type of volcanic explosion that no person has ever seen, but can be seen in geologic history. Also a kimberlite pipe is a type of diatreme, which is another type of pipe filled with breccias from a gaseous explosion. A kimberlite rock formed in the mantle of the earth and can reach temperatures up to 900 degrees Celsius (Pokhilenko 28-29).For diamonds to come up to the surface via kimberlite pipes, they have to be “tectonically activated” and the pipe will eventually connect with the “earth’s surface (Pokhilenko 31).
” “The ocean floor has to slide into the mantle [and] the basaltic rock becomes eclogite, and the organic carbon may become diamond” (About Diamonds 2). The magma from the volcano “originates in the earth at depths of more than 150 km,” likely at “the base of, or just below the thickened plates of the cratons, far deeper than other volcanic magmas. “They [the magma] are said to find their way through fractures in overlying rock and scavenge pieces of debris from these rocks as they ascend. ” In the mess is diamonds.
The process of the upward moving magma is extremely slow and for diamonds to form, “acceleration in essential in ensuring that the diamonds neither alter to graphite as the pressure and temperature decrease, nor are oxidized to carbon dioxide” (Fleet, Hart, Wall 23). Diamonds are carried to the surface in “large pieces of mantle rocks called xenoliths” (Diamond 1).Over time when the diamonds have reached the surface, they can erode and end up in places such as streams or end up being carried away in the ocean. When diamonds are being formed within the earth, a C-center is first formed which is when the “diamond captures nitrogen in the form of separate atomic centers. Then after a process like diffusion, the centers come together and form an A-center. Next, the A-centers come together and form a B-center. A diamond can end up with nitrogen inclusions from formation but those can go away if there is high enough pressure and temperature (Pokhilenko 29).
An area that contains diamonds can be detected by “magnetic anomaly” because some of the areas are surrounded by magnetic materials (Pokhilenko 28). This test is not a definitive test, rather a possible indicator of a diamond-bearing location. One article I read about talks about how a huge kimberlite pipe in Canada was almost missed because it did not test positive for the magnetic materials. Others tests would be needed to determine if diamonds were present such as doing a drilling test hole.
Diamonds are mostly found in the “oldest areas of the continents” such as Africa, Russia, Australia, and South America.A chemical analysis can also aid people in finding the rare kimberlite pipes. The indicator materials can include but are not limited to garnets, chromites, [and certain types of] pyroxene and these sediments can be found “above and downstream from where the pipes occur” (Fleet, Hart, Wall 24). With the test hole, chemical analysis, and magnetic anomaly, there is a lot better chance of finding the kimberlite pipes which is likely to lead to a discovery of diamonds.
In the way of diamond clarity, most people hold them at a higher value if they “colourless and clear. Some diamonds can come out with a tint of blue because of boron, yellow because of nitrogen, pink or red because of an atomic scale defect, green because of radiation damage, or black because of inclusions or irradiation (Fleet, Hart, Wall 26). For thermal properties of diamonds, they take heat away from an object. They essentially pull heat from an object to cool the object down and heat themselves up. A diamond has better thermal conductivity than copper and they are increasingly used to cool things down such as electronics.Also, a diamond will not conduct electricity (The Nature 1). Diamonds have many uses other than for jewelry. Some evidence “suggests that diamonds were being used to polish high quality stone axes in China as early as about 2500 BC.
” Throughout Greece and Rome, diamonds were used in jewelry items such as rings and necklaces. Some diamonds were used in religious jewelry such as crucifixes throughout the sixteenth century and as a status symbol. In the seventeenth century, diamonds were used as a fashion statement (Fleet, Hart, Wall 26).Most diamonds are not good enough to be sold for jewelry purposes. Some diamonds that are not gem quality are used for industrial purposes such as drilling, grinding, or cutting. A lot of industrial uses require good heat conductivity and good hardness.
Diamonds can be ground up into a powder and used in a paste to be used as an abrasive for cleaning purposes (Diamonds 1). Diamonds can be used in plastics, glass, and metal. They can also be included in making everyday things like car engines, eyeglasses, copy machines, computer chips and printers.Diamonds that are used for gem purposes are put into different classifications based on the severity of inclusions in the diamond.
The highest grade is called “FL” or “IF” and they have no inclusions. This particular grade is considered rare because it is hard to find a diamond without any of these flaws. The next grade is called “VVS” because it is very very slightly imperfect. Under a microscope, the amount of inclusions would be almost none. For “VS,” they are known as very slightly imperfect. The only way the inclusions can be seen on this diamond is under a icroscope at 10x magnification. For “SI,” they are known as slightly imperfect because inclusions cannot be seen without aid of a microscope at 10x magnification. The final grade is called “I” because they are imperfect.
With this grade of diamond, inclusions may be seen without aid of a microscope and/or may cause the diamond to be as brilliant (About Diamonds 1).The higher the grade, the more money the diamond is going to cost. Some random physical properties of diamonds include the high refractive index of a diamond. The index is 2. 2 versus a material like glass which is 1. 52 for its index. With diamonds being so refractive, they give off a brilliant looking luster. A diamond also ranks as a 10 on the Mohs hardness scale, which makes a diamond the hardest mineral.
There is very good parallel cleavage in the stone. Diamonds are made of eclogites which means that diamonds may have the type of carbon the was recycled oceanic crust. Another random fact is that all “carbon likely came from the stars. ” Several companies have started to grow diamonds in their labs.
There is a machine made by General Electric that gets up to 1400C and up to 55,000 atmospheres. This process is achieved by chemical vapor deposition which creates a solid with very high purity (The Nature 5). The synthetic diamonds can be used for industrial purposes and they can also be gem quality. The use of synthetic diamonds brings down the price because the synthetics are readily available and have the same hardness as a real diamond. Many long processes are put into creating a diamond.Basically tectonic activity can cause a kimberlite volcano to erupt. Once it erupts, the volcano has to speed up so the diamonds are not compromised.
Then the kimberlite pipe is formed which is also known as a diatreme. The pipes will eventually surface in the top of the earth’s crust and then the pipes have to be detected. Pipes can be located through magnetic anomaly, test drilling, and indicator minerals. The diamonds then have to be extracted out of the ground and can be used for various purposes. Some uses for diamonds include industrial or gem quality.
The majority of the diamonds that are extracted out of the earth are only good enough for industrial uses. Diamonds have many qualities other than their beauty such as hardness, thermal conductivity, good cleavage, and their refractiveness. Gem quality diamonds are classified into grades based on the severity of their inclusions. Several companies have mastered the art of created synthetic diamonds via chemical vapor deposition. The synthetic diamonds are an easy solution the cost of a diamond and the time that a diamond takes to form within the earth.