Diamonds
Fotografiert von Mario Sarto 04. Februar 2004
Volcanic Pipe
American Museum of Natural History
What do these pictures have in common?
Diamonds form under high pressure and heat in the mantle 150-200 km (93-125 miles) below the surface. They don't form on the surface. The the pressure is too low. The stable form of carbon on the surface is graphite.
Diamonds get to the surface in magma from deep in the mantle. This magma erupts in small, but violent, volcanoes. Below these volcanoes are "pipes" filled with volcanic rock, pieces of the mantle, and some diamonds. The rock is called kimberlite after the city of Kimberley, South Africa, where the pipes were first discovered in the 1870s. Click here to see this in action.
In the last 20 years scientists have discovered new sources of diamond. Continental collisions -- a result of plate tectonics -- can subject slices of a crust to immense burial and uplift. In Kazakhstan, for example, diamonds formed in buried crust that returned to Earth's surface. Meteor impacts produce immense pressures, and diamonds can be formed and sprayed among the impact debris. Meteorites also experience impacts themselves and can contain diamonds. (Source: American Museum of Natural History)
There is some really interesting history on this site.
Africa is the richest continent for diamond mining, accounting for roughly 49% of world production. More about where we find diamonds.
Famous, Historic and Notable Diamonds and some good info about how diamonds are evaluated.
17 comments:
This article is interesting to me because I knew diamonds formed from intense pressure, but I wasn't aware that it took place inside of the earth's mantle. I like the news that scientist have began to discover new types of diamonds. I am a believer in "diamonds are a girls best friend" and with this it'll give us better options for picking out the perfect diamond for a unique ring one day.
Britini Irwin
I found it very interesting that the diamonds flow through pipes in the magma. I knew that diamonds were formed under pressure and mined from the earth's crust. I also found interesting that after many years scientists have discovered that meteor impacts and continental collisions can also force diamonds to the earth's surface.
- Andrew Hagan
I thought that it was really interesting that diamonds could survive the temperature of magma, and that the process of plate tectonics that we just learned about had something to do with the formation of diamonds. I think that it is cool that the shape of the diamond was much like the shape of that volcano pipe. On YouTube I found a video speaking of the formation of diamonds.
http://www.youtube.com/watch?v=vHPOp69SO9E
Devin Robinson
"Meteorites also experience impacts themselves and can contain diamonds." Meteorites already contain diamonds before hitting Earth? Does that mean that some diamonds aren't formed on Earth, but in space? That'd be interesting but I'm not sure if I've taken that the right way. It's hard to believe the same stuff in my pencil is the same stuff I'd like on my engagement ring. Go figure!
Julie Lisak
I found this article very interesting. I never really knew much about diamonds at all or how they formed. I’ve never really even thought about it, but now that I think about it, they must come from somewhere in the Earth! I think it’s very intriguing how they form in the earth’s mantle from intense pressure. It makes sense that they would come to the surface with magma but it amazing how something so pretty can survive the temperatures of magma. With them being so expensive it’s always nice to hear scientists are finding new forms of them! Keep on the search!
-Kierstyn Bone
This article taught me a lot actually, because I don't know much about diamonds, except that they cost a lot and girls love them! To know that they are formed from intense pressure and that they are formed in the Earth's mantle is incredible. I guess it's true when they say you learn something new every day.
-Jayna Brennan
It's crazy to think that scientists have found another source of diamonds. Does this maybe mean the price of diamonds could decrease because supply would go up? This posting was interested to me because I knew that diamonds obviously aren't just sitting on the surface, but I wasn't aware that they are so deep into the mantle.
This article was very interesting to me and I learned a lot. I didn't know to much about diamonds so it was nice learning that there is some diamonds in pipes that are below the volcanoes.
Patricia Doyle
This article explains why diamonds are such an expensive item. I understood that it takes great effort to obtain diamonds, but I never really knew anything more specific. I would have not guessed Africa to be of such importance to the diamond mining field. 49% is an extremely high number especially for one country.
Michelle Probst
I was always curious how we went about discovering diamonds, considering that it takes intense pressure to form them. As Michelle said Africa in extremely rich in diamonds. This article makes me curious as to why that continent is so rich in diamonds.
Carley Pfleger
How diamonds are made really interests me because it takes such a huge impact to make them and they are so rare. It suprised me though to see that Africa was so involved with the selling of diamonds when everything I usually here about africa is that they have so much poverty.
-Caitlin Corey
I thought it was interesting that this article states that basically a diamond is indistructable. I know that a diamond can only be damaged by another diamond, but I did not know that a diamond could withstand the heat intensity of magma, or that diamonds can be formed by meteors crashing to Earth. Out of all that though, the most interesting thing to me was that if two meteors collide hard enough they can form diamonds in them as well.
Tommy Seelhoefer
I knew diamonds had to be formed under high pressure, but I didn't know that they could be brought to the surface in magma pipes. It seems hard to believe that the diamonds could withstand the high heat of the magma, but that kind of explains why they are so hard and can't be destroyed easily.
Tarah Kohler
Brittyne Griffin
ESCI 111 SEC 001
I'm assuming that Africa is so known for their diamonds because of geologically where it is placed on the map. This is because it's access to the mantle. It's to my knowledge, that the 20th century sparked the manufacturing of diamonds. I always wondered who created the value. Since it may have been a rare mineral back then, it probably went for more money.
I have never really been that interested in diamonds, but it was nice to learn a little more about their origins. It is interesting to think that something so beautiful comes from the Earth.
I never knew that diamonds came from below the earth's surface nor did I know that they come to the surface through magma. Ive never been interested in diamonds so it's pretty cool to learn where they come from.
Rhandi Beaty Section 001
I did not know that diamonds could flow through mantle pipes like that. Pretty impressive how these diamonds form. Also, it is crazy to think about why diamonds are so expensive. Honestly, I think it is crazy to see people pay thousands of dollars for a crystal that has been formed from carbon. However, I guess rarity is the main purpose for the expenses. Moreover, I did already know that Africa was a main diamond source for the world. You should check out the movie Blood Diamond, starring Leonardo Dicaprio. That is an excellent movie that gives the audience an experience of what the African people go through for these diamonds; hense, the name "blood diamond."
-David Kasich
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