MadSci Network: Earth Sciences

Re: How much coal does it take to form a 1 carat diamond?

Date: Wed Jun 11 15:24:01 2003
Posted By: David Smith, Director of Professional Development
Area of science: Earth Sciences
ID: 1054672765.Es

1 carat is, by definition, 200 miligrams or one-fifth of a gram.  Since 
diamond is pure carbon, it takes one-fifth of a gram of pure carbon.  
Diamonds do not generally come from coal, but rather from graphite, which 
is also pure carbon.  It takes one-fifth of a gram of graphite, therefore, 
to make one carat of diamond.  Coal, if it could be buried and heated 
higly enough, would lose variable amounts of water, methane, and other non-
carbon, so it would take a little more than one-fifth of a gram of coal, 
but I cannot give you a precise amount since the percentage of those other 
substances in coal can be quite variable.

How long it takes to grow a diamond is a very difficult one to answer.  
I'm not sure that anyone really knows how fast natural diamonds grow.  We 
do know that most are very old, but they could have formed very quickly 
and then just remained as they were for a long time until they finally 
found their way to the surface.  The rate of mineral growth is determined 
by how quickly atoms are able to wiggle and squirm through the crystal 
structure of neighboring atoms and how far they have to travel.  How fast 
they wiggle and squiggle (technically referred to as diffusion) depends 
directly on the temperature.  Diamonds grow where it is hot, so diffusion 
will be fast, and they could likely grow in anything from a few years to a 
few thousand years.  

The rates of changes are a very important and interesting question in 
geology and one that a lot of geologists are trying to figure out - good 

Dave Smith

Current Queue | Current Queue for Earth Sciences | Earth Sciences archives

Try the links in the MadSci Library for more information on Earth Sciences.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2003. All rights reserved.